TransCore encompass 4 - N Select Valid ID Code Criteria

Encompass 4 Reader System Guide
7-12
first three and the first four items, respectivel
y.
Note: A
new ID can fail the filter test and not be transmitted; however, it remains
stored in the comparison register.
The uniqueness test’s time limit is set by Command #441. If an
ID is buffered, it will
not be accepted again unless it arrives at the reader more than the programmed time
interval from the previous arrival or until the receipt of one or more other IDs reset the
uniqueness.
Reader response:
Done
420N Select Valid ID Code Criteria
Command #420N directs the reader to validate an ID received only after it has been
obtained a specified number of times in sequence. Values for N are 0 through 3 (Table
7-7). The factory setting is one acquisition (N = 0).
Table 7-7 Select Valid Code Commands and Frames
Command Valid Code Frames
4200 1 (factory default)
4201 2
4202 3
4203 4
The validation procedure is executed before the unique ID test (Select Unique ID
Code Criteria [#410N] commands). IDs that do not pass the
validation test are not
reported.
For example, command #420
3 specifies that the same ID must be obtained from the
antenna/RF module 4 times in succession before it is considered for the uniqueness
test. This feature is useful in installations where RF reflections may cause a single tag
to be read multiple times or where an occasional ID might be read from fringe areas
440 Reset Uniqueness
Command 440 causes the ID filtering process set by Select Unique ID Code Criteria
(#410N) to restart. It is used in conjunction with the Variable Timeout #44N) com-
mands. This command provides a method to
end all uniqueness timers.
44N Set Uniqueness Timeout
Places a time limit on the uniqueness criterion set by Select Unique ID Code Criteria
(#410N). The parameter N sets the number of minutes on the timeout clock. The fac-
tory setting is two minutes (N =
1).
Command Timeout Clock