Omron V680S-HMD64-EIP User Manual page 98

Section 6
Functions
 FIFO Repeat
When the Reader/Writer receives a command execution request from the host device, it automatically
detects RF Tags in the communications field and communicates with them. After successfully
communicating with an RF Tag once, operation for that RF Tag is stopped. This process is repeated
until the execution request is cleared. The Reader/Writer does not communicate with the RF tag that
has completed communication until the RF tag is out of the communication area.
The Reader/Writer does not communicate with the RF tag once communicated until the following
conditions are satisfied.
•The RF tag goes out of the communication area.
•The Reader/Writer communicates with another RF tag.
You can use the FIFO Repeat communications option to perform communications with RF Tags in
order as they move past the Reader/Writer even when there is limited space between the RF Tags. If
there is more than one RF Tag for which operation is possible in the communications field of the
Antenna at the same time, normal communications will not be possible. Make sure that there is never
more than one RF Tag for which operation is possible in the communications field of the Antenna at the
same time.
RF Tag
Host device
Host device
Reader/Writer
RF Tag operation
FIFO Repeat communications cannot be used for communicating with V680-D1KP RF Tags.
When the communications option is "FIFO Repeat", no notice (error response) is sent to the host device even if an RF
Tag missing error or communications error occurs.
Refer to Time Charts in Section 7 Host Communications Specifications for details of Time charts of each communications options.
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RFID System
96
User's Manual
(EtherNet/IP TM )
Reader/Writer
Reader/Writer FIFO Repeat communications
Reader/Writer Response
RF Tag Communications processing
Waiting for RF Tag
RF Tag A
Communications start when an operable RF Tag enters the
communications field. The operation of RF Tags that have
normally completed communications is stopped. If the RF
tag that completed communication normally moves out of
the communication area and the reader / writer further
communicates with another RF tag, the RF tag is ready to
communicate again.
Response
Waiting for RF Tag Waiting for RF Tag
RF Tag B RF Tag C
Response
Processing completed.