Single Access And Fifo Access Functions - Omron V720 Series User Manual

3-2 Tag Access Functions

3-2-2 Single Access and FIFO Access Functions

Single Access Mode
FIFO Access Mode
Use this mode to communicate with only one tag within the RFID Unit
communications area.
The time required for communications with the tag is shorter compared with
FIFO access mode.
FIFO (First In First Out) access mode enables reading tags in order as they
enter the antenna communications range. Tags with which communications
have been completed are prohibited from being accessed again, so even if
tags with which communications have been completed are still within range of
the antenna, communications will be possible with new tags as they enter the
communications range. When two or more tags enter the antenna
communications range at the same time, a communications error will occur.
When a tag to which access has been prohibited moves out of the
communications area, communications with it will be possible again if it
reenters the antenna communications range.
The above diagram shows an example of a tag inspection line.
When the distance between tags is small, two tags may enter the RFID Unit
communications range at the same time. If this happens when in Single
Access Mode, a communications error will occur, or even if read/write appears
to have been performed, there is no way to know which of the two tags was
read. In FIFO Access Mode, tags entering communications range can be read
or written to in order, so this mode is suited to applications such as a tag
inspection line, in which the order of access is important.
Section 3-2
3-8