User Manual

CHAPTER 6: COMMAND PROTOCOLS
COBALT HF RFID CONTROLLERS OPERATOR’S MANUAL
P/N: 17-1320 REV 01 (03-06) PAGE 68 OF 116
6.3.4 CBx - Response Packet Structure
After performing a command, the Cobalt HF RFID Controller will issue a host-bound
response message. Below is the packet structure of a standard CBx response message.
WORD
#
RESPONSE PACKET
PARAMETER
MSB LSB
01
Overall Length: 2-byte value indicating the
number of “words” in the response packet.
This value will always be at least 6 words.
0x00
06 + (number of
additional data
words retrieved)
02
AA in MSB
Command Echo: single-byte value
indicating the command that was performed
in LSB.
0xAA Command Echo
03
Instance Counter in MSB
(see description below)
Node ID Echo in LSB (will be 0x01 for the
Cobalt -IND)
Instance
Counter
Node ID Echo
04
Month and Day timestamp Month DOM
05
Hour and Minute timestamp Hour Minutes
06
Second timestamp in MSB
Number of Additional Data Bytes
Retrieved in LSB
Seconds N-bytes
07
Retrieved Data – (bytes 1 & 2) used to hold
2-bytes of retrieved data (when applicable).
D1 D2
08
Retrieved Data – (bytes 3 & 4) used to hold
2-bytes of retrieved data (when applicable).
D3 D4
Table 6-4: CBx - Response Packet Structure
I
NSTANCE C OUNTER
The Instance Counter is a one-byte value used by a Subnet16 Gateway or Subnet16
Hub to track the number of responses generated by a given Node ID number. The
Gateway/Hub tallies in its internal RAM separate Instance Counter values for each Node
ID. The Instance Counter value is incremented by one following each response. If, for
example, 10 responses were generated by the controller assigned Node ID 01, its
Instance Counter value will read 10. When the Gateway/Hub is power cycled or
rebooted, all Instance Counter values will be reset to zero (0x00).