BlackKite, Vehicle Tracking System User Manual
Rev. 1.4.0
Zilogic Systems
Page 49
Bytes
Meaning
20
Timestamp Tag
90 62 DA 52
Timestamp
CF D8
Checksum CRC-16 (Modbus)
The ACK message for the above MAIN / HEAD / ALERT message is shown below.
02 CF D8
The meaning of each byte in the packet is listed in the following table.
Bytes
Meaning
02
Type ACK
CF D8
Received Packet Checksum
9.7. Archive
Messages are stored in the archive, in the following situations.
1. GSM Signal is too low.
2. Server is not accessible.
3. Server is accessible, but ACK is not received or received ACK is incorrect.
The messages in the archive are transmitted, when the link to the server is restored. The messages
in the archive are transmitted with the earliest messages first.
During transmission of archived messages, if a new MAIN or ALERT message is triggered, then the
MAIN and ALERT message will be transmitted immediately.