C
HAPTER
4
A
LIEN
R
EADER
P
ROTOCOL
R
EADER
I
NTERFACE
G
UIDE
D
OC
. C
ONTROL
# 8101938-000 R
EV
05
69
If an reader acquisition (which depends mainly on the AcquireCycles and
AcquireCount attributes) takes longer than the AutoStopTimer value, the
acquisition will complete before moving to the evaluate state.
AutoStopTimer Examples
Command
Response
>get AutoStopTimer
AutoStopTimer(ms) = 0
Command
Response
>set AutoStopTimer = 1000
AutoStopTimer (ms) = 1000
A
UTO
S
TOP
T
IMER AND THE
ALR-9770
In the ALR-9770, the AutoStopTimer plays a dual role – it also specifies the time
the reader spends performing a single read cycle, whether a single AutoMode
cycle, or an interactive "get TagList" command.
The ALR-9770 schedules its allowed tag-acquisition time by first equally dividing
the AutoStopTimer value among the specified tag protocols, and then dividing
among the antennas.
AutoStopTimer
(ms)
protocol1 protocol2
a1
a2
a3
a1
a2
a3
For all Class 1 tags, the antenna arbitration algorithm is optimized for maximizing
the read rate of the tags in the field. For Class 0 tags, each antenna is given
112ms of search time. Thus, time division for antennas within a protocol cannot
be specified. When specifying the AutoStopTimer for a search over multiple tag
protocols, it is important to keep in mind the worst case of the multiple protocols.
To calculate a minimum value for AutoStopTimer, determine which protocol will
take the longest to read its tag population, then multiply that value by the number
of protocols and number of antennas.
AutoStopTimer
min
= max( NumTags
Class1
*TimePerTag
Class1
,
NumTags
Class0
*TimePerTag
Class0
) * #Protocols * #Antennas
Typical time to read a Class1 tag is 16ms
Typical time to read a Class0 tag is 1.4ms
What happens if the AutoStopTimer is too small? The reader may not search
using all protocols, and/or it may not have time to search all specified antennas.
For instance, it is desired to read a mixed population of 20 Class1 and 20 Class0
tags, on three antennas. If a small timeout is used (250ms), the reader schedules
its time as follows:
Содержание ALR-8780
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