User's Manual

Table Of Contents
Anticollision Index
The Anticollision Index controls the tag reading algorithm to achieve the
fastest reading speed for the number of tags expected in the reading field at
any given moment. It can also disable the multiple tag-in-field feature.
The Anticollision Index should be set in relation to the maximum number
of tags possibly present in the reading field at one time. Setting the
Anticollision Index higher increases the number of tags that will be expected
to be read in the field. Lowering the Index speeds up the tag read operation.
Selecting the Anticollision Index is therefore a tradeoff choice between the
number of tags in the reading field, and the time required to read/write to
them. Regardless of the index setting, ALL tags present will be read. The
index simply makes the process more efficient.
None of the Anticollision Index values will absolutely limit the number of
tags that can be read by the LRP820. The following table can assist you in
setting the Index value, but tests should be done to find the best value. The
allowed values are from 0 to 7.
Anticollision Index Max number of tags
0 1 (*)
1 2-4
2 4-8
3 8-16
4 16-32
5 32-64
6 64-128
7 >128
(*) anticollision disabled
Some commands return or have as a parameter, the Serial Number (SN).
The tag serial number is a unique read-only, 64 bit (8 bytes) code in the tag
memory. SN commands can be used to selectively write to a specific tag,
identified by the SN. Target tag can be identified with a previous SN read
command.
Note that the anticollision commands, except SN Block Write, SN Fill and
Tag Search All, will return a response packet only after the timeout is ex
-
pired. If the command has the Anticollision Index set to 0, then a response
will be returned after the first successful operation.
Copyright © 2000 Escort Memory Systems
48 LRP820-Series Long-Range Passive Reader/Writer