The wireless sensors will send a periodic supervisory message so that a backend system can verify that the device is still alive and to report error conditions.
The supervisory message also contains a payload that contains the status (current) of the sensor.
Supervisory Message: 0x01
0 Supervisory error codes
1 Current Sensor State (different for each sensor type)
2 Battery level
The current sensor state (byte 1 of the supervisory message) is defined by the individual data sheets.
Byte 2 is used if there is a second sensor state to report.
The battery level (byte 3 of the supervisory message) is a two-digit battery voltage.
It is designed to be human-readable. For example, if the battery voltage is 2.9V, byte 3 would be 0x29.
Supervisory Error Codes: Bit Definitions
7:5 Not used
4 Tamper detected since last reset
3 Current tamper state
2 Error with last downlink
1 Battery Low (under 2.75V)
0 Radio Comm Error. Communication with the integrated radio has failed and device has been reset.
Example of Supervisory Message for a Contact Sensor:
1 0 01 08 01 30
1 Protocol Version (currently always 0x1)
0 Packet Counter (increments by 1 each message and wraps from 0xF to 0x0)
01 Message Type Code (Supervisory Message = 0x01)
08 Error Codes (Current Tamper State = True / Untampered)
01 Current Sensor State (Contacts Open = 0x01)
30 Current Battery Level (3.0V = 0x30)