Asynchronous Protocol; General Description - Honeywell HG4930 Installation And Interface Manual

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Asynchronous Protocol

General Description

The IMU supports the asynchronous RS-422 compatible protocol. Each Asynchronous output
frame will open with an IMU address byte that can be used as a synching byte.
The asynchronous 600/100 Hz data protocol is as specified in Table 3 – Control Message (0x01)
Format and Table 7 – Inertial Message (0x02) Format.
The start of sequential message transmissions is on the average 1/600 seconds ±0.01% apart,
with a repeating pattern of five control message transmissions followed by one inertial message
transmission.
The 600 Hz control data output consists of the angular rates, linear acceleration, and IMU status
words in message ID 0x01 and 0x02. The angular and linear data is filtered and sampled at 1800 Hz.
The 1800 Hz filtered angular and linear data is decimated for 600 Hz control data.
The 100 Hz navigation data output consists of incremental (or "delta") angles and velocities in
message ID 0x02. The navigation data is unfiltered 1800 Hz sensor data which is summed to the
navigation data rate (100 Hz). Accurate attitude and position calculations require that all messages
be received and used.
The order of transmission is Least Significant (LS) bit first; LS byte first; LS 16 bit word first. Only
gyro, accelerometer, and temperature data is signed.
The transmit baud rate will be 1Mbits/sec with 1 start bit, 8 data bits, 1 stop bit, and no parity.