GBK51948 RHINO2
Installation Manual Issue 5
Figure 65: Packet structure — 1 Hz Data
7.7.3.2.6 Packet transmission and timing — Full Data packet
The transmission of a packet begins with a dummy element (0x00, 0x00). This is sent in
case the external receiving device is in a low-power sleep mode, which is particularly likely
at key-on. The dummy element has no meaning other than to wake up the external device,
so this can be safely ignored by the external device.
Figure 66: Packet transmission — Full Data packet
After transmitting the dummy element, there is a delay of approximately one second before
the first data element is transmitted. This first element has two roles: firstly, its ID byte
indicates the start of the data, and secondly, its data byte corresponds to the data protocol
version. The ID byte is always 0x01; the data byte, at the time of writing is 0x01,
corresponding to version 1.
Subsequent data elements are transmitted with a 40 ms delay between each element (see
Figure 66).
The last element in the packet is the checksum, whose value can be used by the external
device to validate the packet. This element, being the final element sent, also signals the
end of the packet transfer to the external device. The checksum ID is always 0xFF and the
checksum value is the 2's complement
1
of the 8-bit sum of all the preceding bytes in the
packet, including the checksum ID (0xFF).
Note 1: For more information on the operation of the 2's complement checksum, contact Dynamic.
Page 136 - Diagnostics
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