R
EADER
F
UNDAMENTALS
C
HAPTER
2
R
EADER
I
NTERFACE
G
UIDE
D
OC
. C
ONTROL
# 8101938-000 R
EV
05
12
At any time, a programmatic call can be made to the reader to retrieve this list of
tags.
PersistTime
The “persist time” defines the duration between the time a tag was last read and
the time it is automatically purged from the TagList. Setting this value to a small
time (~1 second) will cause the TagList to contain only what the reader has seen
in the last second, i.e., a fair representation of what the reader sees at any one
time. Setting the persist time to a long duration allows a history of tags to be built
up. For example, setting the persist time to 3600 seconds allows a list to be built
up detailing all the tags that were read over the last hour.
Setting PersistTime to –1 has the special effect of keeping tags on the list
indefinitely until the TagList is delivered to a host, at which point the TagList is
cleared. This is the default value, and the only value allowed on the ALR-9770.
Tag Details
Each entry in the TagList contains a number of sub fields: the Tag's unique ID,
the read count (the number of times the tag has been read in the current
session), the discovery time (the time the tag was first seen), the last observed
time, the antenna (the antenna ID that the tag was last read from), and others.
TagList Size
The ALR-9800's TagList can hold up to 6000 tag entries. Other Alien RFID
readers can handle up to 1000 entries.
Reading Tags over the Network
The Alien RFID reader provides two methods with which to read tags: Interactive
Mode and Autonomous Mode.
Interactive Mode
- the controlling application issues commands to the
reader to read tags. This command will always immediately return with a
list of tags in the reader's field of view.
Autonomous Mode -
the reader constantly reads tags, and may initiate
a conversation with a network listener when certain events arise.
8000 0100 8820 FFA4
8000 0100 8820 3F02
8000 0400 0232 3F06
8020 0150 2057 3F12
8000 0200 8020 3F16
8000 0100 8820 3F09
New tags detected are added to the
TagList.
Reader TagList...
All tags listed are active.
Tags not read for a while are
removed from the list.
Содержание ALR-8780
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