Datalogic GWY-01-PBS-01, Reference Manual

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GWY-01-PBS-01
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4.3 CBX - RESPONSE PACKET STRUCTURE
After performing a command, the Gateway or RFID controller will issue a host-bound
response packet. Below is the packet structure of a standard CBx response message.
Word # Response Packet Element MSB LSB
01 Overall Length : 2-byte integer indicating
the number of “ words ” in the response
packet. This value will always be at least 6
(+ number of any data words retrieved).
0x00 0x06 + (number
of any retrieved
words)
02 0xAA in MSB
Command Echo in LSB
0xAA <Command
Echo>
03 Instance Counter : 1-byte value indicating
the number of responses generated by the
Node ID identified in the LSB (
see details
below ).
Node ID Echo : 1-byte value indicating the
Node ID of the controller that performed
the command.
<IC> <Node ID
Echo>
04 Month and Day Timestamp <Month> <Day>
05 Hour and Minute Timestamp <Hour> <Minute>
06
Second Timestamp in MSB
Additional Data Length in LSB: 1-byte
value indicates number of additional bytes
retrieved.
<Second> <N-bytes>
07 Retrieved Data Bytes 1 and 2: holds 2
bytes of retrieved data from tag reads,
serial numbers, etc. (when applicable)
<D1> <D2>
Table 4: CBx - Response Packet Structure
4.3.1 Instance Counter
The
Instance Counter is a one-byte value used by the Subnet16 Gateway to track the
number of responses generated by the controller at a given Node ID. The Gateway tallies, in
its internal RAM, separate Instance Counter values for each Node ID.
A Node ID’s Instance Counter will be incremented by
one following each response. If, for
example, the controller at Node 01 has generated 10 responses, its Instance Counter value
will read 0x0A. However, when the Gateway is rebooted or power-cycled, the Instance
Counter values for all Node IDs will be reset to zero (0x00).