User Manual

CHAPTER 6: COMMAND PROTOCOLS
COBALT HF RFID CONTROLLERS OPERATOR’S MANUAL
P/N: 17-1320 REV 01 (03-06) PAGE 67 OF 116
6.3.3 CBx - Command Packet Structure
As noted, CBx commands contain a minimum of six words. Below is the structure of a
standard CBx command packet. For the Cobalt HF-CNTL-485-01 model, refer to the
Subnet16 Gateway or Subnet16 Hub - Operator’s Manuals.
WORD
#
COMMAND PACKET PARAMETER MSB LSB
01
Overall Length: 2-byte integer indicating the number
of 16-bit “words” in the entire command packet. This
value will always be at least 6, as each command has
a minimum of 12-bytes (or 6 words). Overall Length
will increase when additional data words are used in
the command (for fills, writes, etc.).
0x00
0x06 +
(number of
additional data
words, if any)
02
AA in MSB
Command ID: single-byte value indicating command
to perform in LSB.
0xAA Command ID
03
00 in MSB
Node ID: single-byte Node ID number of the controller
to which the command is intended. (Must be 0x01 for
Cobalt -IND).
0x00 0x01
04
Timeout Value: 2-byte integer representing the length
of time allowed for the completion of the command,
measured in 1 millisecond units (when applicable).
Timeout
MSB
Timeout LSB
05
Start Address: 2-byte integer indicating the location of
tag memory where the Read/Write operation will begin
(when applicable).
Start MSB Start LSB
06
Read/Write Length: 2-byte integer indicating the
number of bytes that are to be Read/Written beginning
at the Start Address (when applicable).
Length
MSB
Length LSB
07
Additional Data – (bytes 1 & 2) used to hold 2-bytes
of data used for writes and fills (when applicable).
D1 D2
08
Additional Data – (bytes 3 & 4): used to hold 2-bytes
of data for writes and fills (when applicable).
D3 D4
Table 6-3: CBx - Command Packet Structure