5-2 Control Procedures for Each Communication
5-2
5-8
5-2-2 FIFO Access
In FIFO (first-in, first-out) access, communications with Tags entering the communications area one after
another are carried out in sequence. Once communications with Tags are completed, access to them is
prohibited. Consequently, even if Tags with which communications are already completed exist in the
communications area, a newly entering Tag can be accessed. Simultaneous entering of two or more Tags
causes a communications error. Once an access-prohibited Tag leaves the communications area, access to
the Tag is enabled again.
5-2-2-1 FIFO Trigger Mode
FIFO Trigger Mode is used for communications when the Tag is present in a resting condition
in the antenna communication area. The Reader/Writer prohibits access to the Tag after the
communication has been completed, and keeps the antenna oscillated to maintain the FIFO
access. Under such conditions, the Reader/Writer can issue another FIFO command and
communicate with the next Tag that enteres the communication area, where the previous Tag
with which the communication has been completed is still present. (The commands other than
FIFO Access are rejected).
When there are no accessible Tags in the antenna communication area, the No Tag Error is
returned.To exit the FIFO state, execute Stop Command (ST).
Trigger command
(Host)
(Reader/Writer)
(Tag)
Yet to enter
Communications
Tag
Tag
(Stationary)
(Stationary)
Send a response
Command end
(1) Sends a commands if a Tag is in the R/W
Antenna’s communication range.
(2) The Reader/Writer communicates
according to the command.
(3) On completion of communications, the
Reader/Writer returns a response to the
host.
Note:
Before entering Trigger mode, make sure the Tag is in a resting condition in the antenna communication area.
FIFO
継続状態
(Host)
(Reader/Writer)
FIFO access is maintained.
(3). After the communication has been
completed, the Reader/Writer returns a
response to the host. FIFO access is
maintained.
