Escort LRP2000 6 RFID Communications

LRP2000 Passive Reader/Writer 55

6RFID Communications

Conventions

In this manual, numbers expressed in hexadecimal are appended with “H.” For example, the decimal

number 10 is expressed as “0AH” in hexadecimal. The addresses of the bytes of read/w rite memory within

an RFID tag are numbered from 0 to N, where N is one less than the number of read/write bytes in the tag.

The number of read/write bytes is equal to the Block Size multiplied by the Number of Blocks.

Command protocols

The LRP2000 offers three possible command protocols: ABx Standard, ABx Fast, and ABx ASCII. The

commands in all three protocols have the same basic structure. RFID Command protocols do not affect

the LRP2000 to tag communications.

ABx Standard is a word-based format and shares a common syntax with most existing RFID systems

produced by Escort Memory Systems. ABx Standard was designed for PLCs that handle word-based data

better then byte-based data.

The ABx Fast and ABx ASCII protocols are byte-based packet structures. ABx Fast permits command

execution with fewer total bytes transferred. Escort Memory Systems recommends ABx Fast with

checksum enabled because of faster command execution and increased error detection.

Commands are comprised of a header, a number of parameters, and a command terminator . The he aders

and terminators are unique to each protocol, but are the same for every command within one protocol. For

example, in ABx Standard, every command begins with the one-byte header “AAH,” and ends with the two-

byte terminator “FFFFH.” In ABx Fast and ABx ASCII, every command begins with the 0202H, and ends

with 03H for the default configuration setting. The header and terminator can be changed in the

configuration settings menus.

Like the commands, the responses from the controller comprise a header, a number of response codes

and data, and a response terminator. The headers and terminators are the same for the responses as they

are for the commands. The ABx command set is made of three subsets: the single-tag commands, multi-

tag commands, and user I/O commands. The single-tag commands perform read/write operations on

exactly one tag in the range of the antenna at a time. The presence of more than one tag within the range

of the antenna may cause RFID communication errors. To avoid these errors, the multi-tag commands

allow for simultaneous communication to and from multiple tags within the reading range of the antenna.

The user I/O commands do not communicate with RFID tags. They simply interrogate the status of the

inputs wired to the unit, and set the status of the outputs.