The HMS(health management system) codes in the communication protocols are the diagnostic codes of Mid360, which push periodically by the lidar. They are used to notify some special situations or help users check equipment failures.

1.2.3.1. Composition format

A complete HMS code is a 4 bytes(uint32) code. It consists of an abnormal ID and abnormal level, which is shown below:

Byte[3:2]	Byte[1]	Byte[0]
Abnormal ID	RSVD	Abnormal level

In addition, an abnormal level is a value that is not equal to 0, the value is bigger, and the problem is more serious. As is shown below:

value	level	description
0x01	Info	Notification during normal work
0x02	Warning	There might be problems, which will influence the normal work
0x03	Error	Device work in abnormal situation, please check the problem in time
0x04	fatal	Serious abnormal happened, it might not be recovered, lidar will stop working now

1.2.3.2. Parsing example

For example, an HMS code: 0x01020002, refer to:ref:Composition format, the abnormal ID is 0x0102, and the abnormal level is 0x02(warning)。

Refer to below HMS code table, the code represents “environment temperature is slightly high”, the abnormal level is warning, suggested action is “Please check the environment temperature and losing heat measures”。

1.2.3.3. Diagnostic codes table

abnormal ID	abnormal level	abnormal description	suggested solution
0x0102	warning	Environment temperature is slightly high	Please check the environment temperature and losing heat measures
0x0104	warning	The window is dirty, which will influence the reliability of the point cloud	please clean the window
0x0111	fatal	Abnormal temperature of internal components of the device	Please check the environment temperature and losing heat measures
0x0112	fatal	Abnormal temperature of internal components of the device	Please check the environment temperature and losing heat measures
0x0113	fatal	IMU stopped working	Please try to restart the device to restore
0x0114	error	Environment temperature is high	Please check the environment temperature and losing heat measures
0x0115	fatal	Environment temperature beyond the limit, the device has stopped working	Please check the environment temperature and losing heat measures
0x0116	fatal	Abnormal external voltage	Please check the external voltage
0x0117	fatal	Abnormal lidar parameters	Please try to restart the device to restore
0x0201	warning	Scan module is heating	Please wait for the scan module heating
0x0210-0x0219	error	Scan module is abnormal, the system is trying to recover	Please wait, if it lasts too long, please try restarting the device to restore
0x0210-0x0219	fatal	Scan module is abnormal	Please try to restart the device to restore
0x0401	warning	Communication link was linked down, now it is recovered	please check the communication link
0x0402	warning	PTP time synchronization stop or time gap is too big	Please check the PTP time source
0x0403	warning	The version of PTP is 1588-v2.1, device don’t support this version	Please replace 1588-v2.1 version with 1588.2.0 version
0x0404	warning	PPS time synchronization abnormal	Please check the PPS and GPS signal
0x0405	warning	There was an exception in time synchronization	Please check the exception reason
0x0406	warning	Time synchronization accuracy is low	Please check the time source
0x0407	warning	PPS time synchronization fails because of loss of GPS signal	Please check the GPS signal
0x0408	warning	PPS time synchronization fails because of loss of PPS signal	Please check the PPS signal
0x0409	warning	GPS signal is abnormal	Please check the GPS time source
0x040A	warning	The PTP and GPTP signals exist at the same time	Please check the network topology, use PTP or GPTP alone to synchronize