User's Manual

Table Of Contents
ABxF Command 97 (97H): SN Block Read All
DESCRIPTION
Read a block of data from all RFID tags-in-field or all those with the speci
-
fied Family ID. Data will be returned with the serial number of the corre
-
sponding tag.
DISCUSSION
This command is used to read segments of data from contiguous areas of tag
memory. It is capable of handling up to 48 bytes of data transferred to the
host with one command if there is no tag family ID. 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 response to this command will contain the serial number of the respond
-
ing tags preceding the data from those tags. The termination packet is trans
-
mitted when the timeout expires. Each packet will be sent to the host as soon
as it is available. The returned serial numbers can be used to read/write to
tags-in-field via the SN Block Read/Write command.
The SN Block Read All consists of Family ID and an Anticollision Index, a
start address and length, followed by a timeout value and the message termi-
nator, <ETX>, as shown below.
A special termination packet is sent when the timeout expires. If the
Anticollision Index is 0, a response is returned when the operation is suc-
cessfully completed on 1 tag, or when the timeout expires. A termination
packet is not sent for successful completion if the Anticollision Index is 0.
If the read range exceeds the last tag address, the LRP820 will return an
error message in the status byte.
Copyright © 2000 Escort Memory Systems
134 LRP820-Series Long-Range Passive Reader/Writer