Command and Programming Manual

Rev 1.7.2

Applicable to the public commands and data interfaces of HiPNUC IMU / AHRS / MRU products

Specific features are subject to the actual product model, firmware version, and delivered configuration

Document Scope and Version

About This Manual

This manual is the Command and Programming Reference for HiPNUC IMU / AHRS / MRU products, intended for engineers who need to interface directly with the module, configure parameters, parse data, or integrate it into a higher-level system.

Applicable products: the public programming interfaces of HiPNUC IMU / AHRS / MRU standard products. Actual functionality depends on the specific product model, firmware version, and delivered configuration; sensors, CAN, RS-485, or MRU functions that are not enabled produce no corresponding output. This manual covers only the programming and data interfaces; for pin definitions, mechanical dimensions, power supply, and electrical specifications, refer to the hardware manual of the corresponding product.

Applicable firmware version: commands differ slightly between firmware versions. To check: send LOG VERSION over the serial port, or view it in the CHCenter host software, then select the corresponding manual according to the table below.

Your hardware firmware version	Corresponding manual version	Where to get it
1.7.1 and above	Rev 1.7.2	This manual (this document)
1.7.0 and below	Rev 1.3.0	imu_cum_cn_150_170.pdf

Note: version number conversion: the APP_VER returned by LOG VERSION is an integer-encoded value: major version = APP_VER / 100, minor version = (APP_VER % 100) / 10, revision = APP_VER % 10 (all divisions are integer divisions, rounded down). For example, APP_VER=172 indicates firmware 1.7.2. CHCenter displays the dotted version directly, and the two sources are consistent.

Manual structure:

Chapter	Contents	Intended reader
1	Document Scope and Version	Confirm product, firmware, and reading path
2	Basic Conventions (frames / data types / status word)	Required reading before parsing data
3	Product Features and Configuration	Configure module functions
4	Magnetic Calibration and Magnetic Environment	Required reading before configuring 9-axis absolute heading
5	ASCII Command Reference	Quick command syntax lookup
6	Unified Data Dictionary	Cross-protocol physical-quantity semantics
7	Serial Binary Protocol (HI91 / HI83)	Parse binary output
8	Modbus RTU Protocol	Integrate RS-485
9	CAN Protocol (J1939 / CANopen)	Integrate CAN
Appendix	A Attitude Mathematics / B Firmware Upgrade / C Bandwidth / D Factory Default Configuration / E Acronyms / F Development Resources	Reference

Reader paths:

Goal	Read first	Then read
Configure serial port, operating mode, mounting orientation	"Product Features and Configuration"	"ASCII Command Reference", Appendix "Factory Default Configuration"
Parse HI91 / HI83 binary data	"Basic Conventions", "Unified Data Dictionary"	"Serial Binary Protocol"
Integrate Modbus / J1939 / CANopen	"Basic Conventions", "Unified Data Dictionary"	"Modbus RTU Protocol", "CAN Protocol"
Use 9-axis absolute heading	"Operating Mode"	"Magnetic Calibration and Magnetic Environment"
Use MRU wave compensation output	"Wave Compensation / MRU Output"	"Unified Data Dictionary", "Serial Binary Protocol", "Modbus RTU Protocol"
Estimate bandwidth or check default configuration	Appendix "Output Bandwidth and Baud Rate"	Appendix "Factory Default Configuration"

Notational conventions: command keywords, registers, and hexadecimal values are marked in monospace font; callout boxes use Warning (misuse may cause parsing errors, corrupted configuration, or abnormal accuracy/communication) and Note (supplementary explanations and examples); unified definitions of frames, byte order, and scale factors are given in "Basic Conventions"; common abbreviations and terms are listed in the Appendix "Acronyms and Glossary".

Quick Start Procedure

For first-time integration, it is recommended to complete the following minimal closed loop in order; after confirming the data is correct, proceed to the corresponding protocol chapter for system integration.

Step	Action	Verification
1	Connect power, ground, and the communication interface according to the hardware manual	The host software or serial tool can open the port
2	Use 8N1 on the serial port, default `115200 bps`; send `LOG VERSION`	`PNAME`, `SN`, and `APP_VER` can be read
3	Parse data according to the "Unified Data Dictionary" and the corresponding protocol chapter	At rest, acceleration magnitude is about 1 G and angular rate is close to 0

Basic Conventions

This chapter centrally defines the coordinate systems, attitude representations, heading conventions, data types and byte order, timestamps, and status words used throughout the manual. Every protocol chapter references this chapter and does not redefine them. Read this chapter before parsing any data.

Coordinate Systems and Direction Conventions

The module involves three right-handed coordinate systems:

Frame	Symbol	Definition
Sensor frame	b (body frame)	Rigidly attached to the module; the X/Y/Z axis directions are printed on the housing/PCB silkscreen. All raw IMU quantities (acceleration, angular rate, magnetic field) are expressed in this frame.
User frame	—	Obtained by mapping the sensor frame through the mounting orientation `URFR` (see "Mounting Orientation"). With the default `24` it coincides with the sensor frame.
World frame	n (world frame)	The reference frame for attitude; defaults to East-North-Up ENU, switchable to North-West-Up NWU (`CONFIG IMU COORD`).

East-North-Up (ENU): the X axis points East, the Y axis points North, the Z axis points Up. North-West-Up (NWU): the X axis points North, the Y axis points West, the Z axis points Up. Both are right-handed frames.

The positive rotation direction follows the right-hand rule: point the right thumb along the positive axis, and the direction in which the fingers curl is the positive rotation direction about that axis.

Attitude Representation

The module simultaneously outputs two attitude representations: Euler angles and quaternion.

Euler angles: roll roll, pitch pitch, heading yaw, in degrees. Under the default ENU, the 312 rotation order is used (first rotate about Z by yaw, then about X by pitch, and finally about Y by roll) — under this convention pitch is about the X axis and roll is about the Y axis (counter-intuitive; see Appendix A for details). After switching to NWU, the 321 order is used (about Z→Y→X), becoming roll about the X axis and pitch about the Y axis, opposite to ENU (see Appendix A for details). Ranges: roll ∈ [−180°, 180°], pitch ∈ [−90°, 90°], yaw ∈ [−180°, 180°].
Quaternion: order WXYZ ( $q_{0}$ is the scalar part), representing the rotation $Q_{b 2 n}$ from the body frame to the world frame.

The complete conversion formulas among quaternion ↔ Euler angles ↔ rotation matrix are given in "Appendix A".

Note: pitch ±90° singularity: when pitch approaches ±90°, the Euler angles have a gimbal-lock singularity and roll/yaw are no longer unique. For high-elevation attitudes, use the quaternion.

Heading (yaw) Convention

Warning: heading is the most easily confused point: the module's representation of yaw is not uniform across the different protocols/frames, so refer to the table below for understanding.

Output location	Heading representation	Positive direction
HI91 / HI83 / CANopen	Raw yaw, range ±180°	Counter-clockwise positive (ENU)
Modbus YAW register	Raw yaw, range ±180°	Counter-clockwise positive
J1939 YAW message (first 4 bytes)	0–360°	Clockwise positive
J1939 YAW message (last 4 bytes)	±180°	Counter-clockwise positive

Under the ENU and NWU world frames, the zero reference of yaw points in different directions, and the axis assignment of roll/pitch changes accordingly (312 for ENU, 321 for NWU; see "Attitude Representation"). After switching the frame (CONFIG IMU COORD), reconfirm the heading reference and the Euler-angle convention.

In 9-axis AHRS mode, yaw references magnetic north by default; this product does not output a true-north-corrected heading through the documented public interfaces. If your system requires a true-north heading, the host should apply a correction based on the deployment location, date, and a magnetic-declination model.

Data Types, Byte Order, and Scale Factors

Data types:

Symbol	Meaning	Bytes
u8 / u16 / u32 / u64	Unsigned integer	1 / 2 / 4 / 8
i8 / i16 / i32	Signed integer (two's complement)	1 / 2 / 4
float	IEEE-754 single-precision float	4
double	IEEE-754 double-precision float	8

Byte order:

Protocol	Byte order
HiPNUC binary (HI91/HI83)	Little-endian (low byte first)
J1939 / CANopen	Little-endian
Modbus RTU	Big-endian (2 bytes per register, high byte first)

Bit numbering convention: in this manual all bit fields (such as MAIN_STATUS and the HI83 data bitmap) use bit0 for the least significant bit (LSB), with bitN being the N-th bit counted from the least significant bit; thus the bit mask 0x00000FFF is bit0–bit11, and 0x000000FF is bit0–bit7.

Scale factor convention: in integer protocols the physical quantity is recovered with a scale factor, physical value = raw value × scale factor. For example, a Modbus acceleration raw value of 1000 with a scale factor of 0.00048828 gives a physical value = 0.488 G. Floating-point protocols (the float/double fields of HI91/HI83) are already in engineering units, with a scale factor of 1.

Warning: the same physical quantity has different types/scale factors/units across different protocols; see "Unified Data Dictionary" for details.

Time and Timestamps

The meaning of system_time in the data frame (u32 for HI91, in ms) varies with the synchronization state:

UTC synchronization not completed: a local monotonic millisecond counter wrapping every 24 h, range 0~86,399,999 ms; it contains no date and does not represent absolute UTC;
UTC synchronization completed: the current-day UTC millisecond count (from 00:00:00 of the current day, wrapping every 24 h).

The synchronization state can be determined from the UTC_UNSYNC bit of MAIN_STATUS (see "MAIN_STATUS Status Word"). UTC synchronization is achieved via PPS + a serial time message; for hardware wiring and timing requirements see "Synchronization Function".

Current-day UTC millisecond timestamp:

Item	Value
Range	0 ~ 86,399,999 ms
Corresponds to	00:00:00.000 ~ 23:59:59.999
Resolution	1 ms

When converting to a display time, parse as hh=system_time/3600000, mm=(system_time/60000)%60, ss=(system_time/1000)%60, ms=system_time%1000. Conversion examples:

system_time (ms)	Corresponding current-day UTC time
0	00:00:00.000
3,661,000	01:01:01.000
43,200,000	12:00:00.000
86,399,999	23:59:59.999

Note: the timestamp contains no date or time-zone information and is interpreted as UTC+0 by default; if local time is required, the host should add the time-zone offset. HI83 additionally provides two time fields: system_time_us (u64, local high-resolution microseconds) and utc (full year-month-day hour-minute-second); whether the utc field is valid UTC is likewise determined by UTC_UNSYNC.

MAIN_STATUS Status Word

MAIN_STATUS is a 16-bit status word that appears in outputs such as HI91 and HI83, defined uniformly as follows

Bit	Name	=1 meaning	=0 meaning
0–2	Reserved	—	—
3	WB_CONV	Gyro bias not converged, accuracy is poor (recommend staying static for 3~5 s)	Bias well converged
4	MAG_DIST	In 9-axis mode the runtime magnetic-field confidence is abnormal (field out of range, rotation verification not yet completed, or magnetic disturbance detected), and the heading angle may degrade to inertial hold	Magnetic-field confidence normal, or in 6-axis mode
5	ACC_SAT	Accelerometer range saturated currently or within the last 2 s	No accelerometer saturation for 2 consecutive s
6	GYR_SAT	Gyroscope range saturated currently or within the last 2 s	No gyro saturation for 2 consecutive s
7	ATT_CONV	Attitude estimate not sufficiently converged, accuracy is poor (recommend staying static for a moment)	Attitude accuracy normal
8	Reserved	—	—
9	STATIC	The device is judged to be static	The device is not judged to be static
10	MAG_AIDING	Magnetometer aiding mode enabled (9-axis mode); the actual magnetic update each cycle is still subject to magnetic-field confidence and algorithm de-weighting control	Magnetometer aiding mode off (6-axis mode)
11	UTC_UNSYNC	UTC not synchronized; `system_time` is a local 24 h wrapping millisecond counter	UTC synchronized; `system_time` is the current-day UTC milliseconds
12	SOUT_PULSE	The current data frame corresponds to one SOUT pulse output	The current frame does not correspond to a SOUT pulse
13	Reserved	—	—
14–15	Reserved	—	—

Note: the UTC_UNSYNC bit means "1 indicates not synchronized"; do not misread it literally as "synchronized". SOUT_PULSE is used to time-synchronize and align with the sampling timing of an external acquisition device or host.
Reserved bits: reserved bits are used internally by the firmware and their values are not guaranteed to be 0; the client should mask and ignore all reserved bits and only evaluate the bits defined in this table, to ensure forward compatibility.

Product Features and Configuration

This chapter introduces the module's configuration items, use cases, and operating procedures by function. For specific command syntax, see "ASCII Command Reference"; for output data formats, see "Unified Data Dictionary" and the subsequent protocol chapters.

Operating Mode (Attitude / Heading Profile)

The module selects the attitude / heading profile via CONFIG ATT MODE (see "CONFIG Configuration Commands"). The common public profiles are as follows:

6-axis (VRU) mode: Uses only the accelerometer + gyroscope, outputting relative heading (heading is 0 at power-on), unaffected by magnetic interference, suitable for magnetically complex scenarios such as indoors, robotics, and near motors.
9-axis (AHRS) mode: Fuses the magnetometer, outputting absolute heading (relative to magnetic north). It must be used in a clean magnetic environment with magnetic calibration completed (see "Magnetic Calibration and Magnetic Environment").
Dedicated motion profiles: Optimized for specific body motion constraints, such as humanoid robots, low-speed ground platforms, and low-dynamic inclinometers. For the specific selectable values, see "CONFIG ATT MODE".

Warning: Use 9-axis with caution indoors/on robots: Indoor environments and motor magnetic fields easily interfere with the magnetometer, causing heading errors. For such scenarios, 6-axis mode is recommended as the preferred choice.

Mounting Orientation (URFR)

CONFIG IMU URFR <CODE> (see "CONFIG Configuration Commands") is used to declare the module's mounting orientation, aligning the output to the user's desired Right-Front-Up direction.

CODE is written as a three-digit number ABC (a 2-digit value is equivalent to padding with a leading zero, e.g., 24 = 024): A/B/C indicate which sensor-frame direction the user-frame X/Y/Z axes correspond to, respectively:

Digit	Direction	Digit	Direction
0	+X	1	−X
2	+Y	3	−Y
4	+Z	5	−Z

The right-handed-frame constraint must be satisfied (X × Y = Z). When looking up the table, simply select the corresponding command based on the module's physical orientation; there is no need to manually apply the "user axis → sensor direction" encoding rule above. In the table below, for the 24 valid mountings, "Right / Front / Up" refers to the actual pointing of the sensor X / Y / Z axes in the body (user) frame (which is the inverse viewpoint of the encoding rule above; if you need a custom orientation not in the table, derive it according to the encoding rule starting from the "user axis", and do not directly copy the sensor-axis observation directions of this table):

IMU axis pointing (X, Y, Z)	Command	Description
Right, Front, Up	`URFR 24`	Default horizontal mounting (=024)
Right, Back, Down	`URFR 35`	Flipped upside-down about X (=035)
Right, Down, Front	`URFR 43`	Side mounting (Right+Down)
Right, Up, Back	`URFR 52`	Side mounting (Right+Up)
Left, Front, Down	`URFR 125`	X reversed, Z downward, inverted
Left, Back, Up	`URFR 134`	X/Y reversed, Z upward
Left, Up, Front	`URFR 142`	Left-facing vertical mounting, Y up
Left, Down, Back	`URFR 153`	Left-facing vertical mounting, Y down
Front, Right, Down	`URFR 205`	Forward mounting, X along the vehicle nose
Back, Right, Up	`URFR 214`	Backward mounting, Y to the right
Up, Right, Front	`URFR 240`	Vertical mounting, X up
Down, Right, Back	`URFR 251`	Vertical mounting, X down
Front, Left, Up	`URFR 304`	Forward mounting, Y to the left
Back, Left, Down	`URFR 315`	Backward inverted mounting
Down, Left, Front	`URFR 341`	Left-facing vertical mounting, X down
Up, Left, Back	`URFR 350`	Left-facing vertical mounting, X up
Front, Up, Right	`URFR 402`	Forward vertical mounting, Z to the right
Back, Down, Right	`URFR 413`	Backward vertical mounting
Down, Front, Right	`URFR 421`	Vertical mounting, X down, Z to the right
Up, Back, Right	`URFR 430`	Vertical mounting, X up, Z to the right
Front, Down, Left	`URFR 503`	Forward vertical mounting, Z to the left
Back, Up, Left	`URFR 512`	Backward vertical mounting
Up, Front, Left	`URFR 520`	Vertical mounting, X up, Z to the left
Down, Back, Left	`URFR 531`	Vertical mounting, X down, Z to the left

The world frame (ENU/NWU) is switched via CONFIG IMU COORD; see "CONFIG Configuration Commands".

Attitude Calibration

CONFIG ATT RST (see "CONFIG Configuration Commands") is used for user attitude zero-point operations: heading reset, relative zeroing, auto-leveling, and cancel leveling. The device must be stationary during execution; auto-leveling takes effect only when the device is placed nearly level and upright.

CONFIG USRCAL (see "CONFIG Configuration Commands") is used for user-level gyro scale calibration, calibrating the gyro Z-axis scale factor to reduce the long-term heading accumulation error of a horizontally rotating body. This feature is suitable for controllable horizontal rotation scenarios such as AGVs, large horizontally moving robots, and turntables; it is not suitable for handheld arbitrary rotation or scenarios where the rotation angle cannot be accurately measured. Operating steps:

Place the module together with the body on level, flat ground, with a stable ambient temperature and no strong vibration;
Send CONFIG USRCAL START <ANGLE> (angle 360°~3600°);
Rotate horizontally at a constant 20~100 deg/s through the set angle (any direction, no pausing, no abrupt change);
After the rotation is complete, send CONFIG USRCAL STOP; a successful return is OK. It is recommended that the actual rotation angle, controlled manually or by a turntable, not deviate by more than ±5°; if the actual angle deviates too much from the set angle, the calibration will introduce a new scale error.

Common failure causes: improper rotation (too fast, too slow, pausing midway, or obvious wobbling), environmental vibration, and the actual rotation angle deviating too much from the set value.

Synchronization Function

The module's synchronization function relies on the SYNC_IN/PPS and SOUT pins and covers three categories of use. The figure below shows logic-analyzer-measured waveforms, taking the SYNC_IN trigger mode as an example: a rising edge on SYNC_IN/PPS triggers the output of that frame; the module first outputs the SOUT pre-frame pulse before sending the data frame, and the data frame follows immediately after the falling edge of the pulse. Note that the SOUT pre-frame pulse is generated for every output data frame and does not depend on the SYNC_IN trigger (see "SOUT Synchronous Output" for details).

Figure: Logic-analyzer measurement — after SYNC_IN is triggered, SOUT first outputs the pre-frame pulse, and its falling edge is immediately followed by the serial data frame (5A A5…).

SYNC_IN Synchronous Data Trigger

Triggers data output via an external pulse. After the module detects a rising edge on the SYNC_IN/PPS pin, it outputs the data frame that has been configured for synchronous trigger mode; that frame is no longer sent periodically.

Serial protocol: Use LOG <MSG> ONMARK 1 to configure the target frame as pulse-triggered (see "LOG Command").
J1939: Set the transmission period of the target PGN to 0x8000 (see "J1939 Configuration Protocol").

When this function is not used, the pin is recommended to be left floating or grounded.

PPS Standard Pulse Synchronization

Using the SYNC_IN/PPS pin to receive an external 1PPS pulse, combined with receiving a time message over the serial port, can provide precise UTC time synchronization for delivery configurations with this function enabled. After the module detects a valid PPS rising edge and receives a matching time message, its internal clock automatically aligns to the UTC whole second.

Parameter	Description	Valid Range	Recommended
t0	Interval between rising edges of adjacent pulses	990~1010 ms	1000 ms
t1	Pulse high-level time (pulse width)	1~100 ms	10~50 ms
t2	Time message transmission time	Related to baud rate	—
t3	Delay of the time message relative to the most recent pulse rising edge	Within the firmware pairing window	0~100 ms

Warning: Core requirement: The time message used for synchronization must carry the whole-second UTC time and arrive within the pairing window of the most recent PPS. In engineering practice, it is recommended to send it as close as possible to the PPS rising edge and to keep the phase stable.

Hardware and Interface Requirements:

SYNC_IN/PPS: Rising edge active; high level ≤ 5V (TTL/CMOS compatible).
Serial RX: Time message frequency 1~10 Hz (1 Hz recommended); the baud rate must match the module's current configuration; only firmware-defined UTC time messages are supported.

The module extracts only the UTC time (hour/minute/second/millisecond) and date (year/month/day) fields from the time message for synchronization, ignoring all other fields. After successful synchronization, the meaning of system_time is described in "Time and Timestamp". This input message format is part of the delivery configuration; if PPS synchronization is required, refer to the delivery documentation of the corresponding product.

SOUT Synchronous Output

SOUT is the synchronous output pin. It is low when there is no data output; before a data frame begins transmitting, it first outputs a high pulse, and the data follows immediately after the falling edge of the pulse. It can be used to trigger devices such as cameras to achieve strict time synchronization. The SOUT_PULSE bit of the corresponding data frame's MAIN_STATUS (see "MAIN_STATUS Status Word") is set to 1.

Multi-function IO Multiplexing (PMUX)

The module provides multiple multi-function pins (IOx), each with a default multiplexed function, which can also be remapped via CONFIG PMUX<n> IO<m> (e.g., CONFIG PMUX2 IO3, see "CONFIG Configuration Commands"):

Function	Name	Direction	Description	Default IO
PMUX1	SYNC_IN/PPS	Input	Synchronous pulse input (see "Synchronization Function")	IO1
PMUX2	SOUT	Output	Pre-frame sync pulse output (see "SOUT Synchronous Output")	IO2
PMUX3	LED	Output	Operating status indicator	IO5

Note: Not all IO pins are brought out on a specific product; see the corresponding product hardware manual for details.

Product-Specific Features

The following features are supported only on specific models or delivery configurations; other models may skip this section.

Inclinometer Output (Only HI50 and Certain Models)

The inclinometer outputs the body's tilt relative to the horizontal plane in "inclination" semantics, suitable for scenarios such as platform leveling, angle monitoring, and construction machinery attitude. The inclination is derived from the attitude solution:

X-axis inclination: Based on roll, with a range of ±180° dual-axis and a configurable 0–360° single-axis;
Y-axis inclination: Based on pitch, with a range of ±90°.

Output locations: HI83 (bit9), Modbus (0x4A / 0x4B), J1939 (PGN 0xFF4A), CANopen (TPDO7); see "Unified Data Dictionary" for the scale factor of each protocol.

Direction and zero point: The output direction of each axis can be independently reversed (0=default, 1=reversed; for J1939 configuration see "J1939 Configuration Protocol"); the inclination zero point is achieved via "attitude relative zeroing" (CONFIG ATT RST 2, see "CONFIG Configuration Commands"; the CANopen equivalent is 0x20A5 in "CANopen Configuration Commands"). After configuration, a reset or power cycle is recommended to recheck.

Wave Compensation / MRU Output (Heave / Surge / Sway)

The MRU delivery configuration is used to estimate the periodic motion of ships or offshore platforms, outputting three-axis displacement and main-frequency information:

Motion Axis	Description	Output
Heave	Heave	Vertical displacement, frequency
Surge	Surge	Bow-stern direction displacement, frequency
Sway	Sway	Left-right direction displacement, frequency

The data is output via HI83 (bit10 displacement / bit11 frequency) or Modbus (0x4E–0x50 displacement, 0x51–0x53 frequency); see "Unified Data Dictionary". The MRU output reflects the periodic-motion estimation result and is not used as absolute position or track information.

Application scenarios: Ship dynamic monitoring and attitude control, offshore engineering operation compensation (lifting, docking), wave characteristic research, and offshore platform attitude stability analysis.

Usage limitations:

Warning: Important limitations
Applicable only to periodic reciprocating motion; the following cases usually cannot be accurately measured: motion with too long a period (> 30 s), unidirectional linear motion, and step-like displacement.
Zero-mean assumption: The algorithm assumes that the long-term average of the displacement is 0.
Initialization time: A stable 5~20 wave periods are required as the initialization time to obtain correct results.
Frequency response range: The typical wave period is 3~20 s; accuracy decreases beyond this range.

Magnetic Calibration and Magnetic Environment

Magnetic calibration removes the hard-iron/soft-iron disturbances that move together with the module, and is a prerequisite for obtaining a reliable heading angle in 9-axis (AHRS / magnetometer-aided absolute heading) mode. Magnetic calibration is not required when using 6-axis (VRU) mode only.

Note: Procedure overview: Switch to 9-axis mode → slowly rotate each axis together with the carrier in a clean magnetic environment → observe the progress with LOG MCAL STAT → rotate one full turn to verify that the heading angle is continuous and free of jumps.

Applicable Scenarios

9-axis mode is recommended when all of the following conditions are met simultaneously:

Complete at least one user magnetic calibration before using 9-axis mode for the first time;
The operating environment has no obvious spatial magnetic distortion (an open outdoor area is recommended; an indoor environment with a complex magnetic field makes good results hard to guarantee);
The relative position between the module and its mounting carrier (PCB, enclosure, robot, etc.) stays fixed during use.

Warning: Prefer 6-axis indoors: Indoor spatial magnetic distortion cannot be removed by calibration; even if calibration succeeds, the 9-axis heading accuracy may still be worse than in 6-axis mode. For scenarios such as equipment rooms, laboratories, workshops, and underground garages, 6-axis mode is recommended.

Run-time trustworthiness assessment:

Status bit	Meaning	Host handling recommendation
`MAIN_STATUS.MAG_AIDING=1`	Magnetic field participates in heading estimation	Prerequisite for absolute heading availability; still combine with environment assessment
`MAIN_STATUS.MAG_AIDING=0`	Magnetic field does not participate in heading estimation	yaw is handled as 6-axis relative heading and will drift over the long term
`MAIN_STATUS.MAG_DIST=1`	Magnetic interference or abnormal magnetic field state detected	Absolute heading is not trustworthy; investigate the environment first or switch to 6-axis mode

The control system should not judge reliability from the yaw value alone; it should also check the magnetometer-aiding and magnetic-interference status bits in MAIN_STATUS.

Calibration Steps

Step 1: Switch the operating mode

First configure the module to 9-axis mode (CONFIG ATT MODE 1, see "Operating Mode"), then reset or power-cycle, and confirm that magnetometer-aided mode is enabled via MAIN_STATUS.MAG_AIDING=1 or by reading back the configuration.

Step 2: Check the calibration environment

Common sources of magnetic interference: magnets, speakers, magnetic screws, iron furniture, steel fixtures, vehicle chassis, computer monitors, motors and transformers, high-current cables, mobile phone chargers, structural building rebar, etc.

Environment level	Requirement
Best	Open outdoor area, away from buildings and vehicles (distance > 5 m)
For temporary verification only	An indoor area away from steel structures, motors, high-current cables, and magnets; mass-production acceptance should use an open outdoor area, or a fixed site already validated by `B_total` and heading-rotation verification

Warning: Whole-assembly calibration principle: If the module has already been soldered onto the product PCB, uses a magnetic enclosure, or has already been installed on a robot/mechanical equipment, you must rotate and calibrate the entire assembly that is rigidly fixed to the module together. Calibrating the module alone and then installing it into the product will invalidate the calibration.

Step 3: Perform the calibration

Send the calibration command: CONFIG MCAL START (requires firmware version ≥ 1.7.0). Once the module enters the calibration process, it collects three-axis magnetic field samples during rotation and automatically fits the hard-iron/soft-iron compensation parameters; no stop command needs to be sent.

Rotation essentials:

Keep the position essentially unchanged within as small a spatial range as possible, and slowly rotate only the module; if the module is already rigidly fixed to the carrier, rotate the module and carrier together as a whole;
Cover as many attitude directions as possible; for 3D calibration it is recommended to rotate each axis at least 360° (2 to 3 turns recommended), at a uniform speed, with a recommended 20 to 100 deg/s (about 4 to 18 seconds per turn), avoiding staying in the same attitude for a long time;
Calibration usually takes 30 to 60 s.

Recommended rotation scheme: rotate 2 turns about the X axis → 2 turns about the Y axis → 2 turns about the Z axis; or rotate randomly, ensuring every axis undergoes sufficient angular variation while keeping the position as fixed as possible.

Note: Planar mounting (2D) calibration: For mountings that stay essentially level during operation and rotate mainly about the vertical axis (such as AGVs, turntables, vehicles), planar calibration can be started via the command line CONFIG MCAL START 2D, requiring rotation only about the vertical axis. The standard CHCenter calibration button runs the ordinary CONFIG MCAL START process; to force 2D, use the command line or the configuration method specified in the delivery notes. 2D calibration is not detected automatically and must explicitly carry the 2D parameter; it updates only the horizontal-plane parameters and retains the existing Z-axis hard-iron compensation. If a valid 3D calibration has never been performed, the Z-axis hard-iron environment changes, or the carrier will pitch/roll noticeably, use 3D calibration.

Step 4: Query the calibration status

Send LOG MCAL STAT. Example response:

text

STAT=3
PROGRESS=100
QUALITY=72
OK

STAT	Status	Recommended action
0	Currently idle	A new calibration can be started
1	Calibrating	Continue rotating the module; if the module is already rigidly fixed to the carrier, rotate the module and carrier together as a whole
3	Calibration completed	Calibration succeeded, ready for normal use
4	Calibration failed	Refer to the troubleshooting procedure and recalibrate

PROGRESS: ranges 0 to 100, indicating magnetic-sample coverage, not time progress; it shows at most 99 while running and only shows 100 after STAT=3. QUALITY: ranges 0 to 100, indicating the result quality after fitting is completed; manual calibration requires QUALITY ≥ 50 to be judged successful (STAT=3 already satisfies this), and a higher value means a better fit; when STAT=1 it is not used as the quality criterion for the current calibration and may still be the result of the previous calibration.

After calibration succeeds, the hard-iron/soft-iron compensation parameters are immediately applied to the AHRS estimation and written to non-volatile storage; there is no need to run SAVECONFIG separately, nor is a reset required for them to take effect. It is recommended to perform another heading-rotation verification after reset or power-cycle to confirm that the parameters retained through power-down still suit the current mounting and environment.

Step 5: Verify the calibration result

After calibration is complete, place the module level and slowly rotate it one full turn (360°);
Observe the heading angle output: ideally it should vary continuously with the rotation, without unexpected jumps; if the protocol output range is ±180°, wrap-around at the ±180° boundary is allowed; if the output range is 0° to 360°, wrap-around at the 0/360° boundary is allowed;
If the error relative to the reference heading or the closure error over one full turn exceeds ±5°, a non-boundary wrap-around jump appears, or the heading angle does not change with rotation, refer to the troubleshooting procedure below.

Troubleshooting Procedure

When calibration fails (STAT=4) or the verification result is abnormal, check item by item according to the table below, moving to the next item only after the previous one passes (total magnetic field strength B_total = √(Bx² + By² + Bz²), computed from the mag_b three axes):

Order	Check item	Pass criterion	Handling when failed
1	Read the total magnetic field strength B_total at rest	20–60 μT	Below 20 μT (shielded / too weak) or above 60 μT (a magnet nearby / too strong) → move away from the interference source or change location, then recalibrate
2	Whether attitude coverage is sufficient	3D: sufficient coverage on each axis, recommended ≥ 360° per axis; 2D: more than one full turn around the vertical axis in the horizontal plane; rotation speed recommended 20–100 deg/s	Insufficient coverage or staying in the same attitude for a long time → redo the rotation per the essentials, then recalibrate
3	Change of `B_total` when changing orientation at the same location	Difference between maximum and minimum ≤ 10 μT	Exceeds 10 μT (spatial magnetic distortion present); do not judge by the variation of a single axis `Bx/By/Bz` → change location, or switch to 6-axis mode
—	All three items pass but still abnormal	—	Perform calibration again in a clean environment

Frequently Asked Questions

Failure cause	Typical symptom	Solution
Excessive ambient magnetic interference	`STAT=4` or heading-angle jumps	Move to an open outdoor area to calibrate
Non-standard rotation motion	`PROGRESS` grows slowly or stalls	Ensure each axis is rotated sufficiently at a uniform speed
Position moved during rotation	Calibration completes but accuracy is poor	Keep the position fixed during calibration and rotate the attitude only
Module-carrier position changed	Heading-angle error increases after reinstallation	Recalibrate the module and carrier together as a whole

Precautions

Warning: Indoor magnetic field limitation: Indoor spatial magnetic interference cannot be removed by calibration, and the 9-axis heading accuracy depends on the actual degree of magnetic distortion; for the principle, see "Magnetic Interference Types and Calibration Boundaries" in this chapter.

Warning: Fixed-mounting requirement: Sources of magnetic interference must keep a fixed relative position to the module. When the module is mounted on a magnetically permeable rigid body (robot/mechanical equipment/vehicle/ship/tripod/PCB, etc.), the entire system must be rotated and calibrated together; no relative displacement should occur during use, and recalibration is required once they are separated.

Warning: Motor and current influence: If the magnetic field produced by motors, cables, and drivers varies with load, current, or speed, it is a time-varying disturbance and cannot be removed by a single magnetic calibration. Calibration is recommended while the motor is stopped; only when the operating state is stable and the magnetic field is fixed relative to the module may calibration be done in that operating state. If the operating state changes significantly, increase the distance or use 6-axis mode.

Calibration Frequency and Mode Selection

Calibration frequency recommendations:

For a fixed mounting in a stable environment, a single first-time calibration is sufficient;
For mobile applications, recalibration is recommended each time the environment changes;
Recalibrate when the relative position between the module and the carrier changes;
For long-term use (> 1 year), calibration once a year is recommended;
Recalibrate immediately when an abnormal heading-angle error appears.

Mode selection recommendations:

Application scenario	Recommended mode	Reason
Open outdoor environment (UAVs, etc.)	9-axis	Low magnetic interference; an absolute heading angle can be obtained
Indoor environment (AGVs, robots, etc.)	6-axis	Indoor magnetic interference is large; 6-axis is more stable
Near motors / electromagnetic equipment	6-axis	Electromagnetic interference cannot be removed by calibration
Absolute heading angle required	9-axis	Must ensure a stable ambient magnetic field and a completed calibration
Only relative heading angle required	6-axis	The 6-axis heading angle is 0 at power-up, suitable for relative measurement

Magnetic Interference Types and Calibration Boundaries

Magnetic interference can be divided into two major categories by "whether it moves together with the sensor". Only interference that moves with the sensor can be removed by user magnetic calibration; spatial magnetic distortion cannot be removed no matter how you calibrate.

Magnetic interference type	Interference moving with the sensor	Spatial magnetic distortion
Characteristics	The interference source moves as the sensor moves	The interference source does not move with the sensor
Sub-categories	Hard-iron (rigidly attached magnets / PCB / metal enclosure), soft-iron (rigidly attached permeable metal), sensor calibration error	Spatial distortion (rebar / furniture / appliances), temporal distortion (motor / current variation)
Typical interference sources	PCB rigidly fixed to the module, metal enclosure, UAV frame, etc.	Furniture, household appliances, cables, building rebar structures, etc.
Can it be calibrated	Yes	Impossible
Mitigation measures	Can be removed by user magnetic calibration	Calibration cannot remove it and it significantly increases heading-angle error

ASCII Command Reference

Module configuration uses serial ASCII string commands, each terminated by a carriage-return/line-feed \r\n (similar to AT commands). This chapter is the authoritative syntax reference for the commands; for functional background and operating procedures, see "Product Features and Configuration".

Command Format and Conventions

Case: command keywords are uppercase.
Separation: parameters are separated by spaces, e.g. CONFIG IMU URFR 24 (not URFR=24).
Effect and saving:
- Communication commands (SERIALCONFIG, LOG ENABLE/DISABLE, LOG <MSG> ONTIME/ONMARK) usually take effect immediately;
- Long-term configurations are typically persisted once written, but some configurations are loaded only after a reset or power cycle; refer to each command's description and the appendix "Factory Default Configuration" for specifics;
- SAVECONFIG saves all parameters to flash; it is recommended to keep it at the end of the configuration flow for compatibility across firmware versions;
- Restore-type commands (FRESET) save automatically and trigger a reset.
Recommended flow: send configuration → reset or power cycle if necessary → read back to confirm.

Note: This chapter lists common public commands. Compatibility or custom commands are governed by the actual delivery documentation.

Command Overview

Command	Function	Effect
`REBOOT`	Reset the module	Immediate
`SAVECONFIG`	Save all parameters to flash	Immediate
`SERIALCONFIG`	Set the serial baud rate	Immediate
`FRESET`	Restore factory defaults	Immediate (saves automatically and resets)
`CONFIG`	Configure various parameters and operating modes	Per sub-command
`LOG`	Query information / configure data output	Per sub-command

System Commands

REBOOT — Reset the module. Example: REBOOT

SAVECONFIG — Save all parameters to flash. The automatic-save policy may differ across firmware versions, so the host configuration flow should execute this command once after parameter writes are complete.

Example: SAVECONFIG

SERIALCONFIG — Set the serial baud rate. Format: SERIALCONFIG [<COM>] <BAUD>

When <COM> is omitted, the currently connected serial port is configured; when specified (e.g. COM2), the corresponding serial port is configured.
Supported BAUD values (9 in total): 4800 9600 19200 38400 57600 115200 230400 460800 921600

Examples: SERIALCONFIG 115200, SERIALCONFIG COM2 921600

Warning: This command takes effect immediately; after execution you must switch the host to the new baud rate to continue communication.

FRESET — Restore default user configuration; after execution it saves automatically and resets, so use it with caution. Example: FRESET

CONFIG Configuration Commands

Note: The effect timing of CONFIG varies; long-term configurations are persisted once written, but it is generally recommended to read them back for verification after a reset or power cycle. The current public configuration can be read back with LOG COMCONFIG, LOG USRCONFIG, and LOG MCAL STAT (see "LOG Commands").

Event-type or runtime configurations such as ATT RST, IMU URFR, PMUX, and MCAL usually act immediately; long-term configurations such as ATT MODE and IMU COORD are saved when written and loaded after a reset or power cycle.

Operating Mode — `CONFIG ATT MODE <VAL>`

VAL	Mode
0	VRU (6-axis)
1	AHRS (9-axis, magnetometer-aided)
4	Dedicated to humanoid robots
5	Low-speed ground platform (lawn mowers / agricultural machinery / construction machinery, etc.)
7	Low-dynamic / inclinometer

Other delivered modes are governed by the corresponding product documentation. For background, see "Operating Mode".

Attitude Calibration — `CONFIG ATT RST <VAL>`

The device should be stationary during execution; otherwise errors are introduced.

VAL	Action
1	Heading reset: set the current heading angle to zero
2	Set relative zero: set the current Pitch and Roll to zero
3	Auto-leveling: only when both Pitch/Roll are close to 0° (decision threshold 5°), level Pitch/Roll to 0°,0°; otherwise the command has no effect
5	Cancel leveling: restore absolute angles

Note: Other values are for reserved or compatibility purposes and are not used as a public interface.

Mounting Orientation — `CONFIG IMU URFR <CODE>`

CODE is a 2–3 digit orientation code that indicates the mounting orientation of the user frame relative to the sensor frame. For the complete code table (24 legal right-handed frames), see "Mounting Orientation". Example: CONFIG IMU URFR 24 (default horizontal mounting)

World Frame — `CONFIG IMU COORD <VAL>`

VAL	Frame
0	East-North-Up (ENU, default)
4	North-West-Up (NWU)

Multi-function IO Multiplexing — `CONFIG PMUX<n> IO<m>`

n=1~3 is the multiplexed function, and m=1~5 is the target pin. For function definitions, see "Multi-function IO Multiplexing". Example: CONFIG PMUX2 IO1 (set IO1 as synchronous output)

Magnetic Calibration — `CONFIG MCAL START [2D]`

Start a manual magnetic calibration. Without the 2D parameter it is a 3D calibration; CONFIG MCAL START 2D is a planar (rotation about the vertical axis only) calibration. For status queries, see LOG MCAL STAT. For the complete procedure, see "Magnetic Calibration and Magnetic Environment".

User-level Gyro Calibration — `CONFIG USRCAL START <ANGLE>` / `CONFIG USRCAL STOP`

ANGLE: calibration angle, in degrees, with a valid range of 360°~3600°; out-of-range values return an error.
After the rotation is complete, send CONFIG USRCAL STOP; on success it returns OK, otherwise it returns ERR (usually indicating that the main rotation axis is ambiguous or that the scale factor is outside the allowed range).
Example: CONFIG USRCAL START 720 → rotate 2 turns → CONFIG USRCAL STOP. For the complete operating steps and failure troubleshooting, see "Attitude Calibration".

Warning: USRCAL is a precision calibration process. If you set a rotation of 720° but actually rotate 725°, the scale factor will be mis-calibrated by about 0.7%, which instead introduces additional heading error and degrades long-term accuracy. Use it only when a reliable angle reference is available.

LOG Commands

Data Output Switch

LOG ENABLE — globally enable data frame output
LOG DISABLE — globally disable data frame output

Set Data Frame Output Type and Rate — `LOG [<COM>] <MSG> <TYPE> <VALUE>`

COM (optional): the target serial port, e.g. COM2; when omitted, the currently connected serial port is configured.
MSG: the data frame type, commonly HI91, HI83, etc. (governed by the product and serial port configuration).
TYPE: ONTIME (timed) or ONMARK (pulse / software triggered).
VALUE:
- TYPE=ONTIME: output period, in s, range 0.001 (1 kHz) ~ 1 (1 Hz); 0 disables timed output;
- TYPE=ONMARK: 1 triggers on a SYNC_IN/PPS pulse; ONCE triggers once manually.

Examples:

LOG HI91 ONTIME 0.01 — HI91 output at 100 Hz (current serial port)
LOG COM2 HI91 ONTIME 0.01 — output HI91 at 100 Hz on COM2
LOG HI91 ONTIME 0 — disable HI91 output
LOG HI91 ONMARK 1 — configure HI91 to trigger on a SYNC_IN/PPS pulse
LOG HI91 ONMARK ONCE — manually trigger one HI91 output

Warning: At high frame rates (e.g. 500 Hz), the default 115200 baud rate may be insufficient; please raise the baud rate (e.g. 921600). For bandwidth estimation, see the appendix "Output Bandwidth and Baud Rate".

HI83 Field Configuration — `LOG HI83 MAP <BITMAP>`

BITMAP is hexadecimal or decimal, and each bit corresponds to one data segment (bit definitions are in "Variable-type Data Frame (HI83)"). The default is 0x000000FF.

The HI83 fields defined in this manual are bit0-bit11 (field mask: 0x00000FFF). Other bits are not defined in this manual and should not be set by the user; MRU wave compensation uses bit10/bit11.

Command	Description
`LOG HI83 MAP 0x000000FF`	Default combination: acceleration / angular rate / magnetic field / Euler angles / quaternion / system time / UTC / air pressure
`LOG HI83 MAP 0x0000001F`	IMU + attitude basics: acceleration / angular rate / magnetic field / Euler angles / quaternion

Note: MAP only selects which fields HI83 outputs; the frame's switch and rate are still set by LOG HI83 ONTIME <period> (see above). After MAP is written it is persisted; a running HI83 field mapping is loaded with the new value only after a reset or power cycle.

Query Sub-commands

Command	Output Content
`LOG VERSION`	`PNAME`, `BUILD`, `UUID`, `SN`, `APP_VER`, `BL_VER`
`LOG COMCONFIG`	Current serial port configuration: baud rate, `ONTIME` / `ONMARK` settings of each data frame, HI83 `MAP`
`LOG USRCONFIG`	User configuration: mounting orientation (`URFR`), world frame (`COORD`)
`LOG MCAL STAT`	Magnetic calibration status: STAT, PROGRESS, QUALITY

Command Responses and Error Codes

After an ASCII command executes, the result is returned through the same serial port. Success usually echoes OK (or the corresponding query content), while failure returns a message starting with ERROR / ERR. Summary of common responses:

Source	Response	Meaning
General configuration	`OK`	Command accepted
`SERIALCONFIG`	`ERROR: Unsupported baud`	Baud rate is not among the 9 supported values
`CONFIG USRCAL STOP`	`OK` / `ERR`	Gyro calibration succeeded / verification failed (see "CONFIG Configuration Commands")
`LOG MCAL STAT`	`STAT=4`	Magnetic calibration failed (for troubleshooting, see "Magnetic Calibration and Magnetic Environment")
CANopen SDO	abort `0x06090030`	Value out of range
CANopen SDO	abort `0x06010000`	Unsupported access

Note: For the error and response mechanisms of each bus—Modbus / J1939 / CANopen—see the corresponding protocol chapters ("Modbus RTU Protocol", "CAN Protocol").

Unified Data Dictionary

The module supports multiple data output protocols, covering different physical interfaces and upper-layer buses:

Protocol	Physical Interface	Characteristics	See
HiPNUC binary (HI91 / HI83)	RS-232 / TTL / USB	Factory default; HI91 fixed-length, HI83 bitmap-configurable	"Serial Binary Protocol"
Modbus RTU	RS-485	Industrial standard, register read/write	"Modbus RTU Protocol"
J1939	CAN 2.0B	Automotive/industrial bus, periodic PGN broadcast	"CAN Protocol" J1939
CANopen	CAN 2.0B	Standard slave, TPDO output	"CAN Protocol" CANopen

Note: Separation of configuration and data: The module maintains a single set of sensor and status data, and each output protocol is only responsible for packaging it according to its own frame format. Configuration is handled by ASCII commands (see "ASCII Command Reference"); this chapter and the subsequent protocol chapters describe data output.

This chapter defines the canonical semantics of the physical quantities shared across protocols; each physical quantity is defined here once (in SI), and the individual protocol chapters only describe its framing. The tables in this chapter are cross-protocol quick-reference comparisons; for the authoritative scale factor and address of a given protocol, refer to the register/field table in that protocol's chapter. The complete field dictionary of HI83 is given in "Variable-Type Data Frame (HI83)".

Warning: Cross-protocol unit differences: The same physical quantity may have different data types, scale factors, and units across protocols. This is an existing fact of the firmware (not a typo). Decode strictly according to the column for the protocol you are using, and never apply a scale factor across protocols. The scale-factor convention is given in "Data Type, Byte Order, and Scale Factor": physical value = raw value × scale factor.

Decoding Pitfalls at a Glance

The table below lists only items that are easily confused across protocols; for precise item-by-item decoding (address / type / scale / unit), see the register/field table in the protocol chapter you are using.

Physical Quantity	Cross-protocol Pitfall	Consequence of Misapplication
Acceleration	4 decodings: HI91 = G (f32), HI83 = m/s² (f32), Modbus / J1939 = i16 ×0.00048828 → G (±16 G), CANopen = mG (×0.001 G)	Dimension off by 9.8× (G ↔ m/s²) or 1000× (G ↔ mG)
Heading yaw	Dual representation in one frame: J1939 carries both u32 = CW 0–360 and i32 = ±180 in the same frame; HI91 / HI83 / Modbus / CANopen are all CCW/raw	Wrong field → direction and sign fully reversed
System time	Three time bases: HI91 = wall-clock ms, HI83 = uptime μs, Modbus = uptime ms, J1939 = UTC packed; CANopen does not output it	Subtracting across protocols → meaningless timestamp
Inclination	4 encodings: HI83 = f32 deg, Modbus = i16 ×0.011 deg, J1939 = i32 ×0.001 deg, CANopen = i32 ×0.01 deg; HI91 does not output it	Wrong scale / type → wrong value
Angular rate	Varied units / scales: HI91 = deg/s (f32), HI83 = rad/s (f32, off by 57.3×), Modbus / J1939 = i16 ×0.061 → deg/s, CANopen = i16 ×0.1 deg/s (coarser)	Dimension off by 57.3× (deg/s ↔ rad/s) or wrong scale
Euler angles	CANopen scale is coarser: ×0.01 deg (≠ Modbus / J1939 ×0.001 deg; HI91 / HI83 are f32 deg)	Precision / value does not match expectation
Magnetic field	No CANopen TPDO carries the magnetic field	The quantity cannot be found in CANopen

Output Coverage Overview

✓ = the protocol outputs this quantity; — = not output. For exact address / scale / unit, see the register/field table in the protocol chapter you are using.

Physical Quantity	HI91	HI83	Modbus	J1939	CANopen
Acceleration	✓	✓	✓	✓	✓
Angular rate	✓	✓	✓	✓	✓
Magnetic field	✓	✓	✓	✓	—
Roll / Pitch	✓	✓	✓	✓	✓
Heading yaw	✓	✓	✓	✓	✓
Quaternion	✓	✓	✓	✓	✓
Temperature	✓	✓	✓	✓	—
Air pressure	✓	✓	✓	—	✓
System time	✓	✓	✓	✓	—
Inclination	—	✓	✓	✓	✓
Heave / Surge / Sway	—	✓	✓	—	—

Serial Binary Protocol

RS-232, serial TTL, and USB (virtual COM port) are all streaming serial interfaces, and all output using HiPNUC's proprietary binary protocol. This protocol is the module's factory default output protocol. The serial parameters are 8 data bits, no parity, 1 stop bit (8N1), with a factory default baud rate of 115200 bps (see the appendix "Factory Default Configuration").

Frame Format

Field	Value	Length (bytes)	Description
SOF	`5A A5`	2	Start-of-frame sync word
LEN	1–512	2	Payload length (little-endian, excluding SOF/length/CRC)
CRC	—	2	16-bit CRC over SOF, length, and payload (excluding the CRC field itself)
Payload	—	1–512	Composed of several sub-packets; each sub-packet consists of a tag and data, where the tag determines its type and length

Warning: Frame Length Limit: The payload is at most 512 bytes (a full frame is at most 518 bytes). The decoder rejects any payload exceeding 512 bytes outright. When all public HI83 fields defined in this manual are enabled, the payload totals 132 bytes, still within the limit.

Warning: Byte Order: All multi-byte values are little-endian (low byte first). See "Data Types, Byte Order, and Scale Factors" for details.

Factory default output: floating-point IMU data frame (HI91).

Floating-Point IMU Data Frame (HI91)

The payload totals 76 bytes and contains the module status, temperature, raw IMU data, magnetic field, air pressure, and the fused attitude.

Offset	Name	Type	Size	Unit	Description
0	tag	uint8	1	—	Data tag: `0x91`
1	main_status	uint16	2	—	Status word, see "MAIN_STATUS Status Word"
3	temperature	int8	1	°C	Module average temperature
4	air_pressure	float	4	Pa	Air pressure
8	system_time	uint32	4	ms	Timestamp, see "Time and Timestamp"
12	acc_b	float	4×3	G	Acceleration, order XYZ; 1 G ≈ 9.8 m/s²
24	gyr_b	float	4×3	deg/s	Angular rate, order XYZ
36	mag_b	float	4×3	μT	Magnetic field strength, order XYZ
48	roll	float	4	deg	Roll angle
52	pitch	float	4	deg	Pitch angle
56	yaw	float	4	deg	Heading angle
60	quat	float	4×4	—	Quaternion, order WXYZ

Warning: Unit Difference: In HI91 the angular rate unit is deg/s; in HI83 the gyr_b unit is rad/s (a factor of 57.3 between them). Select the correct unit according to the frame type you are parsing.

Variable-Type Data Frame (HI83)

HI83 is a configurable variable-length frame that outputs different data combinations according to data_bitmap, with the frame length changing with the configuration. It suits scenarios where IMU, attitude, time, and other data need to be output simultaneously while controlling bandwidth on demand.

A fixed header (8 bytes) is immediately followed by the data segments selected by data_bitmap. The arrangement order of the data segments is given in "Data Segment Arrangement and Offset Calculation" below; the parser must accumulate offsets in that order and must not infer them from the bit value alone.

Offset	Name	Type	Size	Description
0	tag	uint8	1	Data tag: `0x83`
1	main_status	uint16	2	Status word, see "MAIN_STATUS Status Word"
3	status_ext	uint8	1	Status extension byte; this manual does not define the meaning of its bits, and a generic parser may ignore it
4	data_bitmap	uint32	4	Data bitmap; each bit corresponds to one data segment
8	…	—	Variable	Data segments arranged in the line order below

data_bitmap bit definitions (for configuration, see the HI83 field configuration in "LOG Command"). The table below is the public IMU/AHRS/MRU field dictionary; when a product does not enable the corresponding feature, a field may be 0 or have no valid physical meaning:

Bit	Name	Type	Size	Unit	Description
0	acc_b	float	4×3	m/s²	Body-frame acceleration, order XYZ
1	gyr_b	float	4×3	rad/s	Body-frame angular rate, order XYZ
2	mag_b	float	4×3	μT	Body-frame magnetic field, order XYZ
3	rpy	float	4×3	deg	Euler angles: roll −180~180, pitch −90~90, heading −180~180 (counterclockwise positive)
4	quat	float	4×4	—	Quaternion, order WXYZ
5	system_time_us	uint64	8	μs	Local high-resolution timestamp (microseconds accumulated since power-on, unaffected by time synchronization)
6	utc	—	8	—	UTC time: year offset (1, year-2000, e.g. 24=2024), month (1), day (1), hour (1), minute (1), second (2, unit ms, e.g. 12 s = 12000), reserved (1)
7	air_pressure	float	4	Pa	Air pressure
8	temperature	float	4	°C	Module average temperature
9	inclination	float	4×3	deg	Inclinometer output, order inclination_x / inclination_y / yaw; the third float is the heading angle, not the Z-axis inclination
10	heave_surge_sway	float	4×3	m	MRU displacement: heave, surge, sway
11	heave_surge_sway_frq	float	4×3	Hz	MRU frequency: heave, surge, sway
12–31	Extension	—	—	—	Delivery-specific extension fields, not defined in this manual; generic users should not set these bits

Note: Data Segment Arrangement and Offset Calculation: The public HI83 fields defined in this manual are concatenated in the order bit0–bit11, with the public field mask being 0x00000FFF. Bit12 and above may enable undocumented extension fields, which generic users should not set; do not use an all-enabled configuration such as 0xFFFFFFFF, otherwise the frame length and field semantics cannot be parsed from this manual alone. Unset fields do not appear, and the whole frame shortens accordingly; when parsing, accumulate the offset item by item according to the field sizes in the table.

CRC Check

CRC-16/XMODEM is used (also labeled CRC-16/CCITT in some tools): polynomial 0x1021, initial value 0x0000, no input/output reflection, no final XOR. The check covers SOF (2) + length (2) + payload, excluding the CRC field itself.

/*
    currentCrc: previous crc value, set 0 if it's the first section
    src: source stream data
    lengthInBytes: length
*/
static void crc16_update(uint16_t *currentCrc, const uint8_t *src, uint32_t lengthInBytes)
{
    uint32_t crc = *currentCrc;
    for (uint32_t j = 0; j < lengthInBytes; ++j)
    {
        crc ^= (uint32_t)src[j] << 8;
        for (uint32_t i = 0; i < 8; ++i)
        {
            uint32_t temp = crc << 1;
            if (crc & 0x8000)
                temp ^= 0x1021;
            crc = temp;
        }
    }
    *currentCrc = crc;
}

Frame Parsing Example (HI91)

A HI91 frame is 82 bytes in total: the first 6 bytes are SOF/length/CRC, followed by 76 bytes of payload. Example frame (received into array buf):

text

5A A5 4C 00 14 BB 91 08 15 23 09 A2 C4 47 08 15 1C 00 CC E8 61 BE 9A 35 56 3E 65 EA 72 3F 31 D0 7C BD 75 DD C5 BB 6B D7 24 BC 89 88 FC 40 01 00 6A 41 AB 2A 70 C2 96 D4 50 41 ED 03 43 41 41 F4 F4 C2 CC CA F8 BE 73 6A 19 BE F0 00 1C 3D 8D 37 5C 3F

Field	Type	Raw Value	Parsed Value	Description
SOF	—	`5A A5`	—	Start-of-frame
Payload length	—	`4C 00`	0x004C = 76	76 bytes
CRC	—	`14 BB`	0xBB14	Check value
tag	—	`91`	0x91	payload start
main_status	uint16	`08 15`	0x1508	Status word
temperature	int8	`23`	35	°C
air_pressure	float	`09 A2 C4 47`	100676	Pa
system_time	uint32	`08 15 1C 00`	1840392	ms
acc_b x/y/z	float	…	−0.2206 / 0.2092 / 0.9489	G
gyr_b x/y/z	float	…	−0.0617 / −0.0060 / −0.0101	deg/s
mag_b x/y/z	float	…	7.892 / 14.625 / −60.042	μT
roll / pitch / yaw	float	…	13.052 / 12.189 / −122.477	deg
quat w/x/y/z	float	…	−0.4859 / −0.1498 / 0.0381 / 0.8602	—

C Parsing Example (HI91)

The example below parses one complete HI91 frame. When processing a continuous serial byte stream, first perform frame synchronization and buffering, then pass the complete frame into this function. The example depends on the crc16_update() above; the protocol byte order is little-endian, floating-point numbers are encoded as IEEE-754 single precision, and casting the payload directly into a C struct is not recommended.

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>

#define HIPNUC_SOF0          0x5Au
#define HIPNUC_SOF1          0xA5u
#define HIPNUC_MAX_PAYLOAD   512u
#define HI91_TAG             0x91u
#define HI91_PAYLOAD_LEN     76u

typedef struct {
    uint8_t  tag;          /* 0x91 */
    uint16_t main_status;  /* status word */
    int8_t   temperature;  /* deg C */
    float    pressure;     /* Pa */
    uint32_t timestamp;    /* ms */
    float    acc[3];       /* G        */
    float    gyr[3];       /* deg/s    */
    float    mag[3];       /* uT       */
    float    eul[3];       /* deg      */
    float    quat[4];      /* WXYZ     */
} imu_data_t;

static uint8_t U1(const uint8_t *src)
{
    return src[0];
}

static int8_t I1(const uint8_t *src)
{
    return (int8_t)src[0];
}

static uint16_t U2(const uint8_t *src)
{
    return (uint16_t)src[0] | ((uint16_t)src[1] << 8);
}

static uint32_t U4(const uint8_t *src)
{
    return (uint32_t)src[0] |
           ((uint32_t)src[1] << 8) |
           ((uint32_t)src[2] << 16) |
           ((uint32_t)src[3] << 24);
}

static float R4(const uint8_t *src)
{
    uint32_t raw = U4(src);
    float value;
    memcpy(&value, &raw, sizeof(value));
    return value;
}

bool parse_hi91_frame(const uint8_t *buf, size_t len, imu_data_t *out)
{
    if (buf == NULL || out == NULL) {
        return false;
    }
    if (len < 6u) {
        return false;
    }
    if (buf[0] != HIPNUC_SOF0 || buf[1] != HIPNUC_SOF1) {
        return false;
    }

    uint16_t payload_size = U2(buf + 2);
    if (payload_size > HIPNUC_MAX_PAYLOAD || payload_size != HI91_PAYLOAD_LEN) {
        return false;
    }
    if (len != (size_t)payload_size + 6u) {
        return false;
    }

    uint16_t crc = 0;
    crc16_update(&crc, buf, 4);                  /* SOF + LEN */
    crc16_update(&crc, buf + 6, payload_size);   /* payload */
    if (crc != U2(buf + 4)) {
        return false;
    }

    const uint8_t *data = buf + 6;
    if (U1(data) != HI91_TAG) {
        return false;
    }

    imu_data_t decoded = {0};
    decoded.tag         = U1(data + 0);
    decoded.main_status = U2(data + 1);
    decoded.temperature = I1(data + 3);
    decoded.pressure    = R4(data + 4);
    decoded.timestamp   = U4(data + 8);

    for (int i = 0; i < 3; i++) {
        decoded.acc[i] = R4(data + 12 + (size_t)i * 4u);
        decoded.gyr[i] = R4(data + 24 + (size_t)i * 4u);
        decoded.mag[i] = R4(data + 36 + (size_t)i * 4u);
        decoded.eul[i] = R4(data + 48 + (size_t)i * 4u);
    }
    for (int i = 0; i < 4; i++) {
        decoded.quat[i] = R4(data + 60 + (size_t)i * 4u);
    }

    *out = decoded;
    return true;
}

Modbus RTU Protocol

Modbus is a general-purpose protocol in the industrial automation field. Products with an RS-485 or Ethernet interface typically support Modbus; the specifics depend on the actual model and delivered configuration. By default, the current firmware mounts the Modbus slave on the RS-485 channel corresponding to COM1.

It follows the Modbus RTU specification: data is sent and received in units of registers, with each register being 2 bytes, using big-endian (high byte first), and standard Modbus CRC checking.

Warning: byte order note: Modbus registers are big-endian, unlike the little-endian used by the binary/CAN protocols.

Supported function codes:

0x03 (Read Holding Registers): read one or more registers
0x06 (Write Single Register): write a single register

Factory default node ID: 80 (0x50).

Frame Format

Read registers (0x03) — host request:

Field	Value	Description
ID	1–247	Node ID
FUN	0x03	Function code
ADDR_H / ADDR_L	—	Starting register address (high/low 8 bits)
LEN_H / LEN_L	—	Number of registers to read (high/low 8 bits)
CRC_L / CRC_H	—	CRC (low/high 8 bits)

Read registers (0x03) — slave response: ID, 0x03, LEN(byte count), DATA_H, DATA_L, …, CRC_L, CRC_H

Write register (0x06) — host request / slave response (echoes the same): ID, 0x06, ADDR_H, ADDR_L, DATA_H, DATA_L, CRC_L, CRC_H

Note: When writing an out-of-range value (e.g. a Modbus ID outside 1–247) or executing 0x06 on a read-only register, the slave still echoes the request frame (it does not return an exception frame), but the value does not take effect; reading an undefined address returns 0. After configuring critical parameters, read them back to confirm.

Register List

The table below lists commonly used read and configuration registers. For other configuration items (CAN / serial port / J1939 cycle, etc.), see the corresponding protocol chapter ("CAN Protocol") and the ASCII commands (see "ASCII Command Reference").

Address	Name	Type	R/W	Unit / Scale	Description
0x00	CTRL	u16	W	—	Control register, see below
0x04	UART1_BAUD	u16	R/W	—	Serial port baud rate level
0x05	MD_ID	u16	R/W	—	Modbus ID, valid range 1–247 (factory default 80)
0x06	HEADING_MODE	u16	R/W	—	Operating mode: 0=6-axis (relative heading, 0 at power-on), 1=9-axis (magnetometer fusion, absolute heading); other dedicated modes (4/5/7, etc.) see "CONFIG ATT MODE"
0x34–0x36	ACC X/Y/Z	i16	R	G, ×0.00048828	Acceleration (1 G ≈ 9.8 m/s²)
0x37–0x39	GYR X/Y/Z	i16	R	deg/s, ×0.061035	Angular velocity
0x3A–0x3C	MAG X/Y/Z	i16	R	μT, ×0.030517	Magnetic field strength
0x3D–0x3E	ROLL (H/L)	i32	R	deg, ×0.001	Roll angle (big-endian 32-bit)
0x3F–0x40	PITCH (H/L)	i32	R	deg, ×0.001	Pitch angle
0x41–0x42	YAW (H/L)	i32	R	deg, ×0.001	Heading angle
0x43	TEMP	i16	R	°C, ×0.01	Temperature
0x44–0x45	PRS (H/L)	i32	R	Pa, ×0.01	Air pressure
0x46–0x49	Q0–Q3	i16	R	×0.0001	Quaternion W/X/Y/Z
0x4A	INCLI_X	i16	R	deg, ×0.011	Inclinometer X: dual-axis ±180°; single-axis 0–360°
0x4B	INCLI_Y	i16	R	deg, ×0.011	Inclinometer Y: dual-axis ±90°; reserved on single-axis products
0x4C–0x4D	CPUTIME (H/L)	i32	R	ms	System uptime (cumulative milliseconds since power-on, big-endian 32-bit); always the local running time, not switched to UTC by time synchronization, overflows after about 24.8 days. If you need the current day's UTC milliseconds, use the data frame system_time instead (see "Time and Timestamp")
0x4E–0x50	HEAVE/SURGE/SWAY	i16×3	R	m, ×0.01	MRU heave/surge/sway displacement
0x51–0x53	HEAVE/SURGE/SWAY_FRQ	i16×3	R	Hz, ×0.01	MRU heave/surge/sway frequency
0x70–0x77	PNAME	u16	R	—	Device name (ASCII, 8 registers)
0x78	SW_VERSION	u16	R	—	Software version
0x79	BL_VERSION	u16	R	—	Bootloader version
0x7F–0x82	SN	u16	R	—	Product unique serial number (4 registers)
0xA5	ATT_RST	u16	W	—	Attitude control: `1` heading reset / `2` relative zero / `3` auto-leveling / `5` cancel leveling (see below)
0xA6	URFR	u16	R/W	—	Mounting orientation code, see "Mounting Orientation"

Control register (0x00) write values: 0x0000 save all parameters to flash; 0x0001 restore factory defaults; 0x00FF reset.

ATT_RST (0xA5): 1 heading reset (sets the current heading angle to zero); 2 set relative zero (sets the current Pitch/Roll to zero); 3 auto-leveling — only when the current Pitch/Roll are both close to 0° (threshold 5°) does it level to 0°,0°, otherwise the command has no effect; 5 cancel auto-leveling and restore absolute angles.

Note: Other ATT_RST values are reserved or for compatibility purposes and are not used as a public interface.

Common Configuration Examples

Note: The following examples all use the factory default ID 0x50 as an example; if you have modified the Modbus ID, you must also modify the ID field of the message and recompute the CRC.

Operation	Message (Hex)
Save all parameters to flash	`50 06 00 00 00 00 84 4B`
Restore factory defaults	`50 06 00 00 00 01 45 8B`
Reset	`50 06 00 00 00 FF C4 0B`
Set to 6-axis mode (VAL=0)	`50 06 00 06 00 00 64 4A`
Set to 9-axis mode (VAL=1)	`50 06 00 06 00 01 A5 8A`
Set to low-dynamic/inclinometer mode (VAL=7)	`50 06 00 06 00 07 25 88`
Heading reset (sets the current heading angle to zero)	`50 06 00 A5 00 01 55 A8`
Set relative zero (sets Pitch/Roll to zero)	`50 06 00 A5 00 02 15 A9`
Start auto-leveling	`50 06 00 A5 00 03 D4 69`
Cancel auto-leveling	`50 06 00 A5 00 05 54 6B`

Note: For the operating mode (0x06), DATA = the VAL of "CONFIG ATT MODE" (public values 0/1/4/5/7); for attitude control (0xA5), DATA = the ATT_RST mode code (1/2/3/5, see "ATT_RST (0xA5)" above). After changing DATA, recompute the CRC.

Configure baud rate (0x04):

Target baud rate	Message (ID=0x50)
4800	`50 06 00 04 00 00 C5 8A`
9600	`50 06 00 04 00 01 04 4A`
19200	`50 06 00 04 00 02 44 4B`
38400	`50 06 00 04 00 03 85 8B`
57600	`50 06 00 04 00 04 C4 49`
115200	`50 06 00 04 00 05 05 89`
230400	`50 06 00 04 00 06 45 88`
460800	`50 06 00 04 00 07 84 48`
921600	`50 06 00 04 00 08 C4 4C`

Configure node ID (0x05): format [CURRENT_ID] 06 00 05 00 [NEW_ID] CRC(2B).

Set NEW_ID=0x51: 50 06 00 05 00 51 55 B6

Warning: A node ID change takes effect immediately; subsequent messages must use the new ID. If you are not familiar with constructing Modbus messages, it is recommended to use the host software tool to complete the configuration.

Set mounting orientation (0xA6):

Mounting orientation	Message (ID=0x50)
Horizontal, Z-axis up (default)	`50 06 00 A6 00 18 64 62`
Rotated −90° about X-axis (Y vertical, pointing down)	`50 06 00 A6 00 2B 24 77`
Rotated +90° about X-axis (Y vertical, pointing up)	`50 06 00 A6 00 34 65 BF`
Rotated +90° about Y-axis (X vertical, pointing up)	`50 06 00 A6 02 08 64 CE`
Rotated −90° about Y-axis (X vertical, pointing down)	`50 06 00 A6 01 A5 A5 83`

Note: The message DATA (bytes 5–6) = the decimal value of the URFR mounting orientation code converted to hexadecimal (high byte first), e.g. 24→00 18, 520→02 08, 421→01 A5; for the complete 24 valid mounting orientations, see "Mounting Orientation". After changing the code, recompute the CRC.

Reading Version Information (0x70–0x82)

Request: 50 03 00 70 00 14 49 9F (read 20 registers from 0x70).

Response (example):

text

50 03 28 48 49 31 34 52 32 4E 2D 34 38 35 2D 30 30 30 00 00 98 00 6B 00 00 00 00 00 00 00 00 00 00 04 7D 95 5F 8D 2A 17 08 00 00 4D 0C

The data length 0x28=40 bytes. 48 49 31 34 52 32 4E 2D 34 38 35 2D 30 30 30 is the product name in ASCII (HI14R2N-485-000), followed in order by the software version, Bootloader version, and serial number.

Reading IMU/AHRS Data (0x34–0x4B)

Request: 50 03 00 34 00 18 09 8F (read 24 registers from 0x34).

Response (example):

text

50 03 30 FF 01 03 B0 06 50 FC C9 FF 7C 00 91 01 D5 FD DB FD 27 00 00 21 FF 00 00 7F F6 FF FD 73 E7 ...

The data length 0x30=48 bytes (24 registers). Each physical quantity is converted by its scale factor:

Acceleration (G, ×0.00048828):

Axis	Register value	Raw value	Physical value
X	`FF 01`	−255	−0.1245
Y	`03 B0`	944	0.4609
Z	`06 50`	1616	0.7891

Angular velocity (deg/s, ×0.061035):

Axis	Register value	Raw value	Physical value
X	`FC C9`	−823	−50.232
Y	`FF 7C`	−132	−8.057
Z	`00 91`	145	8.850

Magnetic field (μT, ×0.030517):

Axis	Register value	Raw value	Physical value
X	`01 D5`	469	14.312
Y	`FD DB`	−549	−16.754
Z	`FD 27`	−729	−22.247

Euler angles (deg, ×0.001; i32 big-endian, each axis occupies 2 registers H/L):

Axis	Register value (H L)	Raw value (i32)	Physical value
Roll	`00 00` `21 FF`	0x000021FF = 8703	8.703
Pitch	`00 00` `7F F6`	0x00007FF6 = 32758	32.758
Yaw	`FF FD` `73 E7`	0xFFFD73E7 = −166937	−166.937

Warning: Euler angle byte order: Euler angles are 32-bit big-endian, spanning 2 registers (high word first), which is the most error-prone point — you must first assemble the complete i32 with the high word first, then multiply by the scale factor (see the Yaw row in the table above: FF FD 73 E7 → 0xFFFD73E7 = −166937 → −166.937°).

Reading MRU Data (0x4E–0x53)

Request: 50 03 00 4E 00 06 A8 5E (read 6 registers from 0x4E).

The response data is, in order, HEAVE, SURGE, SWAY, HEAVE_FRQ, SURGE_FRQ, SWAY_FRQ, all signed 16-bit integers. The displacement scale factor is ×0.01 m, and the frequency scale factor is ×0.01 Hz.

CAN Protocol

Two high-level protocols are provided on the CAN bus; one is enabled per the delivery configuration: J1939 (default, based on CAN 2.0B extended frames) and CANopen (standard slave, based on CAN 2.0B standard frames, TPDO output). Products supporting CANFD can additionally output CANFD frame 0 under J1939.

Pre-integration checklist:

Check item	J1939	CANopen
Delivered protocol	Confirm the delivered firmware has J1939 enabled	Confirm the delivered firmware has the CANopen slave enabled (custom firmware)
CAN baud rate	Default 500 kbit/s, actual value per product delivery	Default 500 kbit/s, actual value per product delivery
Node ID / address	Default 8, recommended 1–126	Default 8, recommended 1–126
Frame type	CAN 2.0B extended frame; CANFD frame 0 only on CANFD products	CAN 2.0B standard frame
Default output state	Data PGNs broadcast periodically by default	TPDO off by default; a TPDO period must be written first
Hardware wiring	See the hardware manual for termination resistor, shielding, pinout and transceiver levels	Same as left

J1939 (CAN)

Products supporting CAN output use the J1939 protocol by default, complying with the SAE J1939 standard (a high-level protocol based on CAN 2.0B extended frames). Products supporting CANFD can additionally output CANFD frame 0.

CAN Extended Frame Format

J1939 uses a 29-bit extended identifier:

text

CAN_ID = (P<<26)|(R<<25)|(DP<<24)|(PF<<16)|(PS<<8)|SA

See the figure above for the P/R/DP/PF/PS/SA bit fields. All data PGNs of this product use a manufacturer-specific format (PF=0xFF); for each data PGN, see "PGN Message List".

Warning: Byte order: The J1939 data field is little-endian (low byte first). For example, the 32-bit value 0x12345678 appears in the frame as 78 56 34 12.

Protocol Parameters

Parameter	Default	Options / Notes
CAN nominal baud rate	500 kbit/s	125K / 250K / 500K / 800K / 1000K, per actual product
Frame format	CAN 2.0B extended frame (29-bit); CANFD frame 0 only on CANFD products	Compliant with J1939
Data length	8 bytes; CANFD frame 0 is 64 bytes	By frame type
Frame priority	3	0–7, 0 highest
Node address	8	Publicly recommended to use 1–126; 127 is reserved on some models. Data PGNs are sent to broadcast address 255; do not set the device to 255
Data format	Little-endian	Multi-byte, low byte first

PGN Message List

The table below lists only the publicly documented IMU/AHRS J1939 classic CAN data PGNs of this manual (CAN ID of the form 0x0CFF[PS][SA], priority 3 → high byte 0x0C). For MRU displacement / frequency output, see HI83 or Modbus; for CANFD frame 0, see below, which exists only on CANFD-capable products.

PGN (hex)	PGN (decimal)	PS	Name	Applicability
0xFF2F	65327	0x2F	Time information (UTC or local run time)	All
0xFF34	65332	0x34	Three-axis acceleration	All
0xFF37	65335	0x37	Three-axis angular rate	All
0xFF3A	65338	0x3A	Three-axis magnetic field strength	9-axis products
0xFF3D	65341	0x3D	Pitch/roll angle	All
0xFF41	65345	0x41	Heading angle	All
0xFF46	65350	0x46	Quaternion	All
0xFF4A	65354	0x4A	Inclinometer output	Inclinometer products
0xFF43	65347	0x43	Temperature	All

Data fields of each PGN (unlisted bytes are reserved, fixed 0):

0xFF2F Time information

Byte	Field	Type	Unit	Notes
0–5	Year/Month/Day/Hour/Minute/Second	uint8×6	—	Year, e.g. 24=2024
6–7	Milliseconds	uint16	ms	Little-endian

Example: CAN ID 0x0CFF2F08, data 18 06 12 0E 1E 2D 58 02 → 2024-06-18 14:30:45.600 UTC.

After UTC time synchronization is complete, 0xFF2F outputs valid UTC year/month/day/hour/minute/second; when UTC synchronization is not complete, the year/month/day fields are 0, and the hour/minute/second/millisecond come from the local 24 h wrap-around time and must not be treated as absolute UTC. The synchronization state is judged by MAIN_STATUS.UTC_UNSYNC.

0xFF34 Acceleration / 0xFF37 Angular rate / 0xFF3A Magnetic field (same structure, different scale factors; full scale: acceleration ±16 G, angular rate ±2000°/s, magnetic field ±1000 μT)

Byte	Field	Type	Scale factor	Unit
0–1	X	int16	acceleration 0.00048828 / angular rate 0.061035 / magnetic field 0.030517	G / deg/s / μT
2–3	Y	int16	same as above	same as above
4–5	Z	int16	same as above	same as above

0xFF3D Pitch/roll

Byte	Field	Type	Scale factor	Unit
0–3	Roll	int32	0.001	deg
4–7	Pitch	int32	0.001	deg

0xFF41 Heading (two representations in one frame, see "heading (yaw) convention")

Byte	Field	Type	Scale factor	Unit
0–3	Heading (0–360°, clockwise positive)	uint32	0.001	deg
4–7	Heading (±180°, counter-clockwise positive)	int32	0.001	deg

0xFF46 Quaternion

Byte	Field	Type	Scale factor
0–1 / 2–3 / 4–5 / 6–7	qw / qx / qy / qz	int16	0.0001

0xFF4A Inclinometer (inclinometer products)

Byte	Field	Type	Scale factor	Unit
0–3	X-axis inclination (configurable 0–360° or ±180°)	int32	0.001	deg
4–7	Y-axis inclination (±90°)	int32	0.001	deg

0xFF43 Temperature

Byte	Field	Type	Scale factor	Unit
0–1	Temperature	int16	0.01	°C
2–3	Reserved	—	—	Fixed 0
4–7	Reserved	uint32	—	Fixed placeholder value 999; not pressure, do not parse as pressure

0xFF5A CANFD frame 0

CANFD frame 0 exists only on CANFD-capable products and is used to pack common IMU/AHRS status and attitude data into a single 64-byte data field. Classic CAN products do not output this frame; if the product does not explicitly support CANFD, ignore this subsection.

Offset	Field	Type	Scale factor	Unit
0–1	main_status	uint16	—	See "MAIN_STATUS status word"
2–3	Reserved	uint16	—	Fixed 0
4–7	system_time	uint32	1	ms
8 / 10 / 12	acc x/y/z	int16	0.00048828	G
14 / 16 / 18	gyr x/y/z	int16	0.061035	deg/s
20 / 22 / 24	mag x/y/z	int16	0.030517	μT
26 / 30 / 34	roll / pitch / yaw	int32	0.001	deg
38 / 40 / 42 / 44	qw/qx/qy/qz	int16	0.0001	—
46–47	temperature	int16	0.01	°C
48–63	Reserved	—	—	—

Note: The CAN ID, DBC name, and whether CANFD frame 0 is output by default are subject to the documentation of the CANFD-capable product.

Configuration Protocol

The host reads and writes device parameters through a dedicated configuration PGN.

Configuration frame format: CAN ID = 0x0CEF[DA][SA] (DA = product node ID or broadcast 255, SA = host address). Data payload:

Byte	Field	Type	Notes
0–1	ADDR	uint16	Parameter address (little-endian); for values, see the configuration examples below
2	CMD	uint8	0x06=write, 0x03=read
3	Reserved	uint8	Echoed back verbatim by the device (does not carry a status code); host writes 0
4–7	VAL	uint32	Data value (little-endian)

Configuration response rules:

Request type	Responds?	Response CAN ID	Host handling
Point-to-point write (DA = specific node ID)	Yes	`0x0CEF55[node ID]`	On successful write, returns a request echo
Point-to-point read (DA = specific node ID)	Yes	`0x0CEF55[node ID]`	On successful read, returns ADDR + CMD + VAL
Broadcast write (DA = 255)	No	—	Does not wait for a response; read back to confirm if necessary
Illegal address, value out of range, or unsupported access	No	—	Judged as failure by timeout

The response has destination address 0x55 and source address equal to the device node ID; e.g. the response CAN ID for node 8 is 0x0CEF5508. To simplify receive filtering, the host is recommended to use SA=0x55 when sending configuration requests.

The PGN transmit period is set by writing the period parameter via a configuration frame. Only the period parameters listed in the table below are public configuration items; unlisted parameters are not a general user interface.

Common configuration examples (default node ID=8):

[VAL] is always a 4-byte uint32 little-endian. A 100 ms period is written as 64 00 00 00; SYNC_IN trigger mode is written as 00 80 00 00.

Data payload	Notes
`2F 01 06 00 [VAL]`	PGN 0xFF2F (time information) transmit period
`34 01 06 00 [VAL]`	PGN 0xFF34 (acceleration) transmit period
`37 01 06 00 [VAL]`	PGN 0xFF37 (angular rate) transmit period
`3A 01 06 00 [VAL]`	PGN 0xFF3A (magnetic field) transmit period
`3D 01 06 00 [VAL]`	PGN 0xFF3D (pitch/roll) transmit period
`41 01 06 00 [VAL]`	PGN 0xFF41 (heading) transmit period
`46 01 06 00 [VAL]`	PGN 0xFF46 (quaternion) transmit period
`4A 01 06 00 [VAL]`	PGN 0xFF4A (inclinometer) transmit period
`43 01 06 00 [VAL]`	PGN 0xFF43 (temperature) transmit period
`5A 01 06 00 [VAL]`	CANFD frame 0 transmit period; effective only on CANFD-capable products
`A5 00 06 00 [VAL]`	Attitude control: VAL=1 heading reset / 2 set relative zero / 3 auto-level / 5 cancel leveling
`9D 00 06 00 01 00 00 00`	Globally enable node data output (default)
`9D 00 06 00 00 00 00 00`	Globally disable node data output
`9A 00 06 00 [VAL]`	CAN baud rate: 0=1000K, 1=800K, 2=500K, 3=250K, 4=125K; saved on write, takes effect after reset or power cycle
`9C 00 06 00 [VAL]`	J1939 node ID: recommended 1–126; 127 is reserved on some models; saved on write, takes effect after reset or power cycle
`9E 00 06 00 [VAL]`	Inclinometer X-axis direction: 0=default, 1=reversed
`9F 00 06 00 [VAL]`	Inclinometer Y-axis direction: 0=default, 1=reversed
`00 00 06 00 00 00 00 00`	Save all parameters to flash
`00 00 06 00 01 00 00 00`	Restore factory defaults (auto-save and reset)
`00 00 06 00 FF 00 00 00`	Reset

Period VAL notes: 0 = off; 5/10/20/50/100/200/500/1000 ms are recommended periods; 0x8000 is SYNC_IN trigger mode.

Warning: special period value 0x8000 (SYNC_IN trigger mode): After writing a PGN's transmit period as 0x8000, that PGN is no longer sent periodically and instead outputs one frame on the external SYNC_IN rising edge. For example, setting the VAL of 34 01 06 00 to 00 80 00 00 puts the acceleration PGN into SYNC_IN trigger mode. The standard firmware has this trigger path wired in; whether custom firmware supports it is subject to the delivery notes.

Note: Example: ID=0x0CEF0855, data 37 01 06 00 64 00 00 00 → sets PGN 0xFF37 (angular rate) to a 100 ms period (10 Hz). In this example DA=0x08, SA=0x55; SA can be any host address. If the host filters reception by the response destination address, fix SA=0x55.

Time Synchronization

J1939 PGN 0xFF2F is used only to output the module's current time information, not as a time-sync input. If you need to synchronize the module's internal clock to UTC, use the PPS + serial time message scheme in "Synchronization Function".

CANopen (CAN)

Some products or delivery configurations support CANopen slave communication (whether enabled is subject to the actual model). CANopen uses standard data frames, with common data transmitted via TPDO1/2/3/4/6/7; remote frames and extended frames are not used. TPDOs are triggered asynchronously on a timer; for synchronous mode, see "TPDO Rate and Synchronization Configuration".

Default Settings

Item	Value
CAN nominal baud rate	500 kbit/s
Node ID	8
Initialization state	Operational
TPDO output period	Default 0 = no active output; transmission starts only after each TPDO period is written via SDO (see "TPDO Rate and Synchronization Configuration")

Warning: By factory default, all TPDO periods are 0 (no output). After power-on, CANopen does not actively send data; you must first configure the output period of the required TPDOs per "TPDO Rate and Synchronization Configuration".

TPDO Mapping

Channel	Frame ID	DLC	Data	Type / Scale / Unit
TPDO1	0x180+ID	6	Acceleration X/Y/Z	int16, mG (0.001 G)
TPDO2	0x280+ID	6	Angular rate X/Y/Z	int16, 0.1 deg/s
TPDO3	0x380+ID	6	Euler angles Roll/Pitch/Yaw	int16, 0.01 deg
TPDO4	0x480+ID	8	Quaternion W/X/Y/Z	int16, raw × 0.0001; raw=10000 → 1.0000
TPDO6	0x680+ID	4	Pressure	int32, Pa
TPDO7	0x780+ID	8	Inclinometer X/Y	int32, 0.01 deg

All multi-byte fields are low byte first.

Warning: scale factors differ from other protocols: CANopen acceleration is in mG, angular rate 0.1 deg/s, Euler angles 0.01 deg; do not apply the Modbus/J1939 scale factors (see "Unified Data Dictionary").

Data Parsing Examples

The following examples assume the corresponding TPDO period has been opened per "TPDO Rate and Synchronization Configuration".

Acceleration frame: ID=0x188 (node 8), data 4A 00 1F 00 C8 03

X = 0x004A = 74 → 74 mG; Y = 0x001F = 31 → 31 mG; Z = 0x03C8 = 968 → 968 mG

Angular rate frame: ID=0x288, data 15 00 14 01 34 00

X = 0x0015 = 21 → 2.1 deg/s; Y = 0x0114 = 276 → 27.6 deg/s; Z = 0x0034 = 52 → 5.2 deg/s

The host can use PCAN-View with a PCAN adapter to view in the receive window:

Configuration Commands (SDO)

CANopen expedited SDO is used. The host sends CAN_ID=0x600+ID, and the slave responds with CAN_ID=0x580+ID. The SDO data area is a fixed 8 bytes:

text

CS | Index_L | Index_H | SubIndex | Data0 | Data1 | Data2 | Data3

Both Index and Data are little-endian. Common CS values are as follows:

CS	Direction	Meaning	Data bytes
0x23	Host→Slave	Write 4 bytes	4
0x2B	Host→Slave	Write 2 bytes	2
0x2F	Host→Slave	Write 1 byte	1
0x40	Host→Slave	Read request	0
0x60	Slave→Host	Write success response	0
0x43	Slave→Host	Read 4-byte response	4
0x4B	Slave→Host	Read 2-byte response	2
0x4F	Slave→Host	Read 1-byte response	1
0x80	Slave→Host	SDO abort	4-byte abort code

This product configures common public parameters through manufacturer object indices. The table below lists only the public objects defined in this manual; unlisted objects are not a general user interface—do not derive or access them via manufacturer object indices that are not listed. Multi-byte values are arranged in little-endian when written or read. If the device denies access, it returns a 0x80 abort response; common abort codes are 0x06090030 (value out of range) and 0x06010000 (access not supported).

Common commands (using node ID=8, CAN_ID=0x608 as an example):

Operation	Data
Modify node ID (0x209C, recommended 1–126; 127 is reserved on some models)	`23 9C 20 00 [ID] 00 00 00`
Save all parameters to flash (0x2000)	`23 00 20 00 00 00 00 00`
Reset (0x2000)	`23 00 20 00 FF 00 00 00`
Restore factory defaults (0x2000)	`23 00 20 00 01 00 00 00`
CAN baud rate 1000K (0x209A)	`23 9A 20 00 00 00 00 00`
CAN baud rate 800K	`23 9A 20 00 01 00 00 00`
CAN baud rate 500K	`23 9A 20 00 02 00 00 00`
CAN baud rate 250K	`23 9A 20 00 03 00 00 00`
CAN baud rate 125K	`23 9A 20 00 04 00 00 00`
Attitude relative zero (0x20A5)	`23 A5 20 00 02 00 00 00`
Auto-level	`23 A5 20 00 03 00 00 00`
Cancel leveling / restore absolute angles	`23 A5 20 00 05 00 00 00`
Read node ID (0x209C)	`40 9C 20 00 00 00 00 00`

Note: CANopen parameter persistence: The TPDO period (0x180x.5) and heartbeat (0x1017) take effect immediately after being written; the CAN baud rate (0x209A) and node ID (0x209C) take effect only after a reset (write 0xFF to 0x2000), and after reset the host must also switch to the new baud rate / new node ID. For compatibility across firmware versions, after configuration it is recommended to write 0x00 to 0x2000 to save all parameters to flash.

Warning: After restoring factory defaults, the module automatically saves and resets; use with caution.

TPDO Rate and Synchronization Configuration

TPDO channels map to parameter indices:

Channel	Parameter index	Data
TPDO1	0x1800	Acceleration
TPDO2	0x1801	Angular rate
TPDO3	0x1802	Euler angles
TPDO4	0x1803	Quaternion
TPDO6	0x1804	Pressure
TPDO7	0x1805	Inclinometer

TPDO5 is unused; to remain compatible with existing product definitions, pressure uses TPDO6 and the inclinometer uses TPDO7.

Modify output rate (write sub-index 5, unit ms; 0=off), using acceleration (0x1800) as an example:

2B 00 18 05 00 00 00 00 — off (period=0)
2B 00 18 05 05 00 00 00 — 200 Hz (period=5 ms)
2B 00 18 05 0A 00 00 00 — 100 Hz (period=10 ms)
2B 00 18 05 14 00 00 00 — 50 Hz (period=20 ms)
2B 00 18 05 32 00 00 00 — 20 Hz (period=50 ms)
2B 00 18 05 64 00 00 00 — 10 Hz (period=100 ms)

For the other channels, change the low byte of the index (the 2nd byte of the frame) to 01 (angular rate) / 02 (Euler angles) / 03 (quaternion) / 04 (pressure) / 05 (inclinometer); for example, angular rate at 100 Hz: 2B 01 18 05 0A 00 00 00. This item (rate, sub-index 5) takes effect immediately after being written and is automatically persisted (retained across power loss), with no extra save needed.

Synchronous mode: Writing a TPDO's transmission type [0x180x.2] as 0x01 switches it to synchronous mode (stops asynchronous timing and waits for the sync frame). Using TPDO1 as an example:

2F 00 18 02 01 00 00 00 — set TPDO1 to synchronous mode
2F 00 18 02 FF 00 00 00 — restore TPDO1 to asynchronous mode (default)

Send a CANopen sync frame: CAN_ID=0x80, empty data. All TPDOs in synchronous mode each send one frame, achieving synchronization.

Note: The transmission type (synchronous / asynchronous) is a runtime-only setting and reverts to the asynchronous default (0xFF) after reset or power cycle; it is not retained across power loss. The TPDO rate (sub-index 5) and heartbeat period, however, are retained across power loss.

Heartbeat: Write [0x1017.0] to set the period (ms, 0 disables). Example 2B 17 10 00 64 00 00 00 → 100 ms.

Appendix A — Quaternion / Euler Angles / Rotation Matrix Conversions

This appendix presents the attitude representations adopted by HiPNUC products and the formulas for converting between them. The quaternion order is WXYZ ( $q_{0}$ is the scalar part), and $Q_{b 2 n}$ denotes the rotation from the body frame (b frame) to the world frame (n frame).

Note: Frame convention: The module's world frame defaults to East-North-Up (ENU) and can be configured to North-West-Up (NWU) (CONFIG IMU COORD, see "Coordinate Frames and Orientation Conventions"). The section "East-North-Up (ENU) — 312 rotation order" below gives the ENU conversion formulas (consistent with the module's default output); the section "North-East-Down (NED) — 321 rotation order" gives the NED external-conversion reference commonly used in engineering practice — NED is not a device output configuration defined in this manual. The Euler angles output in NWU use the same 321 axis convention as NED (roll about X, pitch about Y, yaw about Z); only the axis directions differ (NWU: X North / Y West / Z Up). Its Euler convention differs from that of ENU (which is 312): the two have opposite axes for roll/pitch, and their yaw difference is not a constant 90°, so you cannot simply add 90° of yaw to the ENU Euler angles to obtain NWU. To convert, first rotate by 90° about the up axis at the quaternion level, then extract the Euler angles using the 321 order.

Quaternion to Rotation Matrix

Given the quaternion $Q_{b 2 n} = [q_{0}, q_{1}, q_{2}, q_{3}]^{T}$ , the direction cosine matrix is:

C_{b 2 n} = [\begin{matrix} q_{0}^{2} + q_{1}^{2} - q_{2}^{2} - q_{3}^{2} & 2 (q_{1} q_{2} - q_{0} q_{3}) & 2 (q_{1} q_{3} + q_{0} q_{2}) \\ 2 (q_{1} q_{2} + q_{0} q_{3}) & q_{0}^{2} - q_{1}^{2} + q_{2}^{2} - q_{3}^{2} & 2 (q_{2} q_{3} - q_{0} q_{1}) \\ 2 (q_{1} q_{3} - q_{0} q_{2}) & 2 (q_{2} q_{3} + q_{0} q_{1}) & q_{0}^{2} - q_{1}^{2} - q_{2}^{2} + q_{3}^{2} \end{matrix}]

East-North-Up (ENU) — 312 rotation order (Z first, then X, then Y)

Euler angle definitions under the ENU convention:

pitch (θ): rotation angle about the X axis, range $[- \frac{π}{2}, \frac{π}{2}]$
roll (φ): rotation angle about the Y axis, range $[- π, π]$
yaw (ψ): rotation angle about the Z axis, range $[- π, π]$

Quaternion to Euler angles:

\begin{aligned} pitch & = \arcsin (2 (q_{0} q_{1} + q_{2} q_{3})) \\ roll & = - atan 2 (2 (q_{1} q_{3} - q_{0} q_{2}), q_{0}^{2} - q_{1}^{2} - q_{2}^{2} + q_{3}^{2}) \\ yaw & = - atan 2 (2 (q_{1} q_{2} - q_{0} q_{3}), q_{0}^{2} - q_{1}^{2} + q_{2}^{2} - q_{3}^{2}) \end{aligned}

Euler angles to quaternion (let $c_{p} = \cos (\frac{pitch}{2})$ , $s_{p} = \sin (\frac{pitch}{2})$ , with $c_{r} / s_{r}$ and $c_{y} / s_{y}$ defined analogously):

\begin{aligned} q_{0} & = c_{p} c_{r} c_{y} - s_{p} s_{r} s_{y} \\ q_{1} & = s_{p} c_{r} c_{y} - c_{p} s_{r} s_{y} \\ q_{2} & = c_{p} s_{r} c_{y} + s_{p} c_{r} s_{y} \\ q_{3} & = c_{p} c_{r} s_{y} + s_{p} s_{r} c_{y} \end{aligned}

North-East-Down (NED) — 321 rotation order (Z first, then Y, then X)

Euler angle definitions under the NED convention:

pitch (θ): rotation angle about the Y axis, range $[- \frac{π}{2}, \frac{π}{2}]$
roll (φ): rotation angle about the X axis, range $[- π, π]$
yaw (ψ): rotation angle about the Z axis, range $[- π, π]$

Quaternion to Euler angles:

\begin{aligned} roll & = atan 2 (2 (q_{0} q_{1} + q_{2} q_{3}), 1 - 2 (q_{1}^{2} + q_{2}^{2})) \\ pitch & = \arcsin (2 (q_{0} q_{2} - q_{1} q_{3})) \\ yaw & = atan 2 (2 (q_{0} q_{3} + q_{1} q_{2}), 1 - 2 (q_{2}^{2} + q_{3}^{2})) \end{aligned}

Euler angles to quaternion (let $c_{r} = \cos (\frac{roll}{2})$ , $s_{r} = \sin (\frac{roll}{2})$ , with $c_{p} / s_{p}$ and $c_{y} / s_{y}$ defined analogously):

\begin{aligned} q_{0} & = c_{r} c_{p} c_{y} + s_{r} s_{p} s_{y} \\ q_{1} & = s_{r} c_{p} c_{y} - c_{r} s_{p} s_{y} \\ q_{2} & = c_{r} s_{p} c_{y} + s_{r} c_{p} s_{y} \\ q_{3} & = c_{r} c_{p} s_{y} - s_{r} s_{p} c_{y} \end{aligned}

Appendix B — Firmware Upgrade

This product supports firmware upgrade. Please use the CHCenter host software and follow the steps shown below; to obtain the firmware upgrade file (.hex), contact technical support.

Note: Before upgrading, confirm that the firmware version matches the product model (see the version cross-reference table in "About This Manual"). Do not power off during the upgrade.

Appendix C — Output Bandwidth and Baud Rate

Whether a data frame can be output stably depends on whether frame length × frame rate stays within the serial bandwidth. Estimating with 8N1 (10 bit per byte):

max frame rate (Hz) \approx \frac{baud rate / 10}{bytes per frame}

In practice, it is recommended to reserve an additional 10–20% margin on top of the formula above. An HI91 frame is 82 bytes total (6 bytes of header/length/CRC + 76-byte payload); the recommended maximum output frame rate at each baud rate:

Protocol	Bytes per frame	9600	115200	230400	460800	921600
HI91	82	10 Hz	100 Hz	250 Hz	500 Hz	1000 Hz

Note: HI83 uses variable-length frames: its bytes per frame vary with the data_bitmap configuration. Sum the frame length according to the selected fields and substitute it into the formula above for estimation. For example, with the default 0x000000FF (bit0–7), a frame is about 98 bytes (payload 92 + 6 bytes of header/length/CRC); 100 Hz requires about 98 kbit/s, for which 115200 leaves a tight margin and 230400 or higher is recommended. When a high frame rate conflicts with the default 115200 bandwidth, raise the baud rate (e.g. 921600).

Appendix D — Factory Default Configuration

The table below lists the default configuration after factory delivery or restore factory defaults (FRESET) (based on firmware 1.7.2; the actual delivered configuration prevails). The "Effective Timing" column explains when a change takes effect after modification.

Configuration Item	Default Value	Available Range	Effective Timing
Serial baud rate (COM1–4)	115200	4800…921600 (9 steps, see "System Commands")	Immediately (`SERIALCONFIG`)
Default output frame	HI91 @ 100 Hz (COM1, COM2)	—	Immediately (`LOG`)
Other frames (HI83, etc.)	Off	—	Immediately
Operating mode	See product delivery (6-axis / 9-axis)	`CONFIG ATT MODE`	Saved on write; loaded after reset / power cycle
World frame COORD	ENU	ENU / NWU	Saved on write; loaded after reset / power cycle
Mounting orientation URFR	24 (horizontal, Z up)	See "Mounting Orientation"	Immediately (`CONFIG IMU URFR`)
HI83 data_bitmap	`0x000000FF`	See "Variable-Type Data Frame (HI83)"	Saved on write; loaded after reset / power cycle
Modbus node ID	80	1–247	Immediately
CAN node ID	8	Recommended 1–126; 127 reserved on some models	Saved on write; reset / power cycle
CAN nominal baud rate	500 kbit/s for standard firmware	125K…1000K	Saved on write; reset / power cycle
J1939 periodic output master switch	On	0 / 1	Immediately
J1939 default output PGN	Acceleration / angular rate / pitch-roll / heading @ 100 Hz	See "J1939 Configuration Protocol"	Immediately
CANopen TPDO period	All 0 (no output)	See "TPDO Rate and Synchronization Configuration"	Immediately
CANopen heartbeat	Off (0)	0–65535 ms	Immediately

Warning: FRESET side effects: Restoring factory defaults resets the above user configuration; do not rely on FRESET to retain any user-written parameters. See FRESET in "System Commands" for details.

Appendix E — Acronyms and Glossary

The abbreviations and technical terms used in this manual are summarized below (for command keywords such as LOG, CONFIG, SAVECONFIG, and FRESET, see "ASCII Command Reference").

Abbreviation / Term	Full name / Meaning
IMU	Inertial Measurement Unit (accelerometer + gyroscope, optionally with magnetometer)
AHRS	Attitude and Heading Reference System (9-axis, absolute heading)
VRU	Vertical Reference Unit (6-axis, relative heading)
ENU / NWU / NED	East-North-Up / North-West-Up / North-East-Down; ENU/NWU are device configurations, NED is an external conversion reference (see "Coordinate Frames and Orientation Conventions", Appendix A)
URFR	Mounting orientation code, the axis mapping of the user frame relative to the sensor frame (see "Mounting Orientation")
COORD	World frame configuration (ENU / NWU, see "Coordinate Frames and Orientation Conventions", "CONFIG Configuration Commands")
MAIN_STATUS	Main status word, 16-bit (see "MAIN_STATUS Status Word")
MCAL	Magnetometer Calibration (see "Magnetic Calibration and Magnetic Environment")
USRCAL	User-level gyroscope calibration, calibrates the gyroscope Z-axis scale factor (see "Attitude Calibration")
PMUX	Pin Multiplexing, multi-function IO multiplexing (see "Multi-function IO Multiplexing")
SOUT	Sync Output, pre-frame sync output pulse (see "SOUT Synchronous Output")
SYNC_IN / PPS	Sync pulse input / standard pulse-per-second, used for triggering and time synchronization (see "Synchronization Function")
HI91 / HI83	HiPNUC binary data frame types: fixed-length floating-point / variable-length bitmap
SOF	Start of Frame, start-of-frame sync word (`5A A5`)
CRC	Cyclic Redundancy Check
PGN	Parameter Group Number (J1939)
SA / DA	Source / Destination Address (J1939)
TPDO	Transmit PDO, Transmit Process Data Object (CANopen cyclic output)
SDO	Service Data Object (CANopen configuration read/write)
DBC	CAN database file, describing CAN signal definitions, for import into CANoe / BusMaster, etc. (see Appendix "Development Resources and Technical Support")
EDS	Electronic Data Sheet, CANopen Electronic Data Sheet (object dictionary description file, see Appendix "Development Resources and Technical Support")
Heave / Surge / Sway	Heave / surge / sway, the three-axis periodic motion of a vessel (see "Wave Compensation / MRU Output")

Appendix F — Development Resources and Technical Support

The following tools and resources are available for secondary development:

Resource	Purpose	Where to Get It
CHCenter host software	Device connection, parameter configuration, data plotting / attitude visualization, data recording and playback, firmware upgrade	www.hipnuc.com
Binary parsing example	C-language frame parsing: frame reception, CRC check, field-table decoding	See "C-Language Parsing Example (HI91)"
Firmware upgrade	Upgrade via CHCenter; contact technical support for the `.hex` file	See Appendix B
DBC / EDS (CAN)	J1939 DBC and CANopen EDS machine-readable files for import into CANoe / BusMaster / PLC	Contact technical support

Information about new products and resources is available on the official website and WeChat official account.

Website: www.hipnuc.com

WeChat official account:

Telegram:

Command and Programming Manual ​

Document Scope and Version ​

About This Manual ​

Quick Start Procedure ​

Basic Conventions ​

Coordinate Systems and Direction Conventions ​

Attitude Representation ​

Heading (yaw) Convention ​

Data Types, Byte Order, and Scale Factors ​

Time and Timestamps ​

MAIN_STATUS Status Word ​

Product Features and Configuration ​

Operating Mode (Attitude / Heading Profile) ​

Mounting Orientation (URFR) ​

Attitude Calibration ​

Synchronization Function ​

SYNC_IN Synchronous Data Trigger ​

PPS Standard Pulse Synchronization ​

SOUT Synchronous Output ​

Multi-function IO Multiplexing (PMUX) ​

Product-Specific Features ​

Inclinometer Output (Only HI50 and Certain Models) ​

Wave Compensation / MRU Output (Heave / Surge / Sway) ​

Magnetic Calibration and Magnetic Environment ​

Applicable Scenarios ​

Calibration Steps ​

Step 1: Switch the operating mode ​

Step 2: Check the calibration environment ​

Step 3: Perform the calibration ​

Step 4: Query the calibration status ​

Step 5: Verify the calibration result ​

Troubleshooting Procedure ​

Frequently Asked Questions ​

Precautions ​

Calibration Frequency and Mode Selection ​

Magnetic Interference Types and Calibration Boundaries ​

ASCII Command Reference ​

Command Format and Conventions ​

Command Overview ​

System Commands ​

CONFIG Configuration Commands ​

Operating Mode — CONFIG ATT MODE <VAL> ​

Attitude Calibration — CONFIG ATT RST <VAL> ​

Mounting Orientation — CONFIG IMU URFR <CODE> ​

World Frame — CONFIG IMU COORD <VAL> ​

Multi-function IO Multiplexing — CONFIG PMUX<n> IO<m> ​

Magnetic Calibration — CONFIG MCAL START [2D] ​

User-level Gyro Calibration — CONFIG USRCAL START <ANGLE> / CONFIG USRCAL STOP ​

LOG Commands ​

Data Output Switch ​

Set Data Frame Output Type and Rate — LOG [<COM>] <MSG> <TYPE> <VALUE> ​

HI83 Field Configuration — LOG HI83 MAP <BITMAP> ​

Query Sub-commands ​

Command Responses and Error Codes ​

Unified Data Dictionary ​

Decoding Pitfalls at a Glance ​

Output Coverage Overview ​

Serial Binary Protocol ​

Frame Format ​

Floating-Point IMU Data Frame (HI91) ​

Variable-Type Data Frame (HI83) ​

CRC Check ​

Frame Parsing Example (HI91) ​

C Parsing Example (HI91) ​

Modbus RTU Protocol ​

Frame Format ​

Register List ​

Common Configuration Examples ​

Reading Version Information (0x70–0x82) ​

Reading IMU/AHRS Data (0x34–0x4B) ​

Reading MRU Data (0x4E–0x53) ​

CAN Protocol ​

J1939 (CAN) ​

CAN Extended Frame Format ​

Protocol Parameters ​

PGN Message List ​

Configuration Protocol ​

Time Synchronization ​

CANopen (CAN) ​

Default Settings ​

Command and Programming Manual

Document Scope and Version

About This Manual

Quick Start Procedure

Basic Conventions

Coordinate Systems and Direction Conventions

Attitude Representation

Heading (yaw) Convention

Data Types, Byte Order, and Scale Factors

Time and Timestamps

MAIN_STATUS Status Word

Product Features and Configuration

Operating Mode (Attitude / Heading Profile)

Mounting Orientation (URFR)

Attitude Calibration

Synchronization Function

SYNC_IN Synchronous Data Trigger

PPS Standard Pulse Synchronization

SOUT Synchronous Output

Multi-function IO Multiplexing (PMUX)

Product-Specific Features

Inclinometer Output (Only HI50 and Certain Models)

Wave Compensation / MRU Output (Heave / Surge / Sway)

Magnetic Calibration and Magnetic Environment

Applicable Scenarios

Calibration Steps

Step 1: Switch the operating mode

Step 2: Check the calibration environment

Step 3: Perform the calibration

Step 4: Query the calibration status

Step 5: Verify the calibration result

Troubleshooting Procedure

Frequently Asked Questions

Precautions

Calibration Frequency and Mode Selection

Magnetic Interference Types and Calibration Boundaries

ASCII Command Reference

Command Format and Conventions

Command Overview

System Commands

CONFIG Configuration Commands

Operating Mode — `CONFIG ATT MODE <VAL>`

Attitude Calibration — `CONFIG ATT RST <VAL>`

Mounting Orientation — `CONFIG IMU URFR <CODE>`

World Frame — `CONFIG IMU COORD <VAL>`

Multi-function IO Multiplexing — `CONFIG PMUX<n> IO<m>`

Magnetic Calibration — `CONFIG MCAL START [2D]`

User-level Gyro Calibration — `CONFIG USRCAL START <ANGLE>` / `CONFIG USRCAL STOP`

LOG Commands

Data Output Switch

Set Data Frame Output Type and Rate — `LOG [<COM>] <MSG> <TYPE> <VALUE>`

HI83 Field Configuration — `LOG HI83 MAP <BITMAP>`

Query Sub-commands

Command Responses and Error Codes

Unified Data Dictionary

Decoding Pitfalls at a Glance

Output Coverage Overview

Serial Binary Protocol

Frame Format

Floating-Point IMU Data Frame (HI91)

Variable-Type Data Frame (HI83)

CRC Check

Frame Parsing Example (HI91)

C Parsing Example (HI91)

Modbus RTU Protocol

Frame Format

Register List

Common Configuration Examples

Reading Version Information (0x70–0x82)

Reading IMU/AHRS Data (0x34–0x4B)

Reading MRU Data (0x4E–0x53)

CAN Protocol

J1939 (CAN)

CAN Extended Frame Format

Protocol Parameters

PGN Message List

Configuration Protocol

Time Synchronization

CANopen (CAN)

Default Settings