User's Manual

COBALT UHF-SERIES CHAPTER 5: COMMAND PROTOCOLS
PAGE 51 OF 140
5.4 ABX FAST COMMAND PROTOCOL
The default command protocol used by UHF-CNTL-232-02 RFID Controllers for
Point-to-Point data transmission is known as the ABx Fast Command Protocol.
ABx Fast has a single-byte oriented packet structure that permits the rapid execution
of RFID commands while requiring the transfer of a minimal number of bytes.
ABx Fast supports the inclusion of an optional checksum byte. When increased data
integrity is required, the checksum should be utilized. See Section 5.4.3 “Command
Packet Elements” for more on using the checksum parameter.
5.4.1 ABx Fast - Command / Response Procedure
After an RFID command is issued by the host, a packet of data, called the
“Command Packet” is sent to the controller. The command packet contains
information that instructs the controller to perform a certain task.
The controller automatically parses the incoming data packet, searching for a specific
pair of start characters, known as the “Command Header.” In ABx Fast, the
Command Header / Start Characters are 0x02, 0x02. When a valid Command
Header is recognized, the controller then checks for proper formatting and for the
presence of a Command Terminator byte. In ABx Fast, the Command Terminator
byte is 0x03.
Having identified a valid command, the controller will attempt to execute the given
instructions. After which the controller will generate a host-bound response message
containing EITHER the results of the attempted command or an error code if the
operation failed.
Note that all commands generate a response from the controller. Before sending a
second or additional command to a controller, allow the host to first process (remove
from memory) any pending response data.
Table 5-5: ABx Fast - Command Packet Structure