RFID Communications

6.5 ABx Fast Protocol

The ABx Fast protocol differs from the Abx Standard Protocol in that the atomic data element is a byte instead of a 16-bit word. ABx Fast commands and responses also contain a two-byte word to indicate the size of the packet being sent. ABx Fast also supports the use of a one-byte checksum.

Packet Size

The ABx Fast protocol requires that the size of the packet be included following the terminator in every packet. All parameters and data between the packet size byte and the checksum (if used), or terminator bytes (if not using the checksum) must be accounted for in the packet size word. The packet size will be the same with or without a checksum.

Checksum

The optional checksum must be enabled from the operating mode menu to be available. The checksum is calculated by adding all the byte values in the packet (less the values in the header, checksum if present, and terminator), discarding byte overflow, and subtracting the byte sum from FFH. Thus, when the packet length through the checksum are added as byte values, the sum will be FFH.

Example

The following is a typical command using a checksum.

Field

Contents

Header

0202H

 

 

Command Size

0003H

 

 

Command Code

01H

 

 

Timeout

07D0H

 

 

Checksum

24H

 

 

Terminator

03H

 

 

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Escort LRP2000 manual ABx Fast Protocol, Packet Size, Checksum, Field Contents