User's Manual

Table Of Contents
ABxF Command 85 (85H): Block Read All
DESCRIPTION
Read a block of data from all RFID tags-in-field or all those with the speci
-
fied Family ID.
DISCUSSION
This command is used to read segments of data from contiguous areas of tag
memory. The timeout value is given in 1 msec increments and can have a
value of 1EH to FFFEH (65,534 ms). When the timeout is set to 0, the
LRP820 will return a syntax error.
The Block Read All consists of a Family ID, an Anticollision Index, a start
address and length, followed by a timeout value and a message terminator as
shown below.
If the read length exceeds the last tag address, the LRP820 will return an in-
valid format error message (error code 21H). A special termination packet is
sent when the timeout expires. If the Anticollision Index is set to 0, a
response is returned after successful completion of the operation to 1 tag, or
when the timeout expires. When the Anticollision Index is 0, no special
termination packet is sent after timeout.
Field Content
Header <STX><STX>
Command Size Packet length in bytes excluding the header, command size, checksum and
terminator bytes.
Command 85H
Family ID Tag Family ID - 00H = all tags
Anticollision Index Number of tags expected
Start Address 2-byte value for the starting tag address
Block Size 2-byte value for the length of the read in number of bytes
Timeout 2-byte value for timeout in 1 ms units. (1EH - FFFEH)
Checksum Optional Checksum
Terminator <ETX>
NOTE:
This command can not be used with a MUX32 interface.
Copyright © 2000 Escort Memory Systems
110 LRP820-Series Long-Range Passive Reader/Writer