User Manual

CHAPTER 6: COMMAND PROTOCOLS
COBALT HF RFID CONTROLLERS OPERATOR’S MANUAL
P/N: 17-1320 REV 01 (03-06) PAGE 64 OF 116
T IMEOUT VALUE PARAMETER
ABx Fast commands include a two-byte Timeout Value parameter (measured in
increments of one millisecond) that is used to limit the length of time that the Cobalt HF
will attempt to complete a specified operation.
The maximum Timeout Value is 0xFFFE or 65,534 milliseconds (slightly longer than one
minute). Setting a long Timeout Value does not necessarily mean that a command will
take any longer to execute. This value only represents the period of time for which the
Cobalt HF will attempt execution of the command.
IMPORTANT
During write commands, the tag must remain within the antenna’s RF field until the write
operation completes successfully, or until the Timeout Value has expired.
If a write operation is not completed before the tag leaves the controller’s RF field, data
may be incompletely written.
C HECKSUM PARAMETER
The ABx Fast Command Protocol supports the inclusion of an additional checksum byte
that is used to verify the integrity of data being transmitted between host and controller.
The checksum is calculated by adding together (summing) the byte values in the
command packet (less the Header, Checksum and Terminator parameters), and then
subtracting the total byte sum from 0xFF. Therefore, when the byte values of each
parameter (from Command Size to Checksum) are added together, the byte value sum
will equal 0xFF.
To enable the use of the checksum parameter, download the RFID Dashboard Utility
from
www.ems-rfid.com
, and use it to set the ABx Protocol parameter to ABx Fast with
Checksum.