RFID Communications
73 LRP2000 Passive Reader/Writer
6.4.13 ABxS Command 85H: Read All
DESCRIPTION
Command 85H reads data from all RFID tags-in-field, or those tags with the specified Family ID.
DISCUSSION
This command is used to read segments of data from contiguous areas of tag memory. It is capable of
handling up to 1 kByte of data transferred to the host with one command. The timeout value is given in 1
ms increments and can have a value of 001EH to FFFEH (65,534 ms). When the timeout is set to 0, the
controller will return a syntax error message 21H. The Read All consists of Tag Family ID and Reserved
Byte, a start address and number of bytes, followed by a timeout value and the message terminator,
FFFFH. If the read length exceeds the last tag address, the controller returns a syntax error message 21H.
The data read from the tag is returned in the LSB of the register, and the MSB is always 00H. A special
termination packet (AAH FFH) is sent after the timeout expires. The controller returns a response after the
timeout expires. The command returns a response after the successful operation or when the timeout
expires.
Field Remarks
Command Command number in hex preceded by AAH
Tag Family Tag Family ID - 00H = all tags
Reserved Byte 00H
Start Address Tag address where the read will start
Read Length Number of tag addresses to be read
Timeout Timeout value given in 1 ms units (001EH - FFFEH)
Message Terminator FFFFH