Communications Method
Section 5-8
5-59
5-8-2-4 Polling Auto Mode
If an Auto command is used when a single host controls more than one Reader/Writer, the commu-
nications path between the host and one of the Reader/Writers to which the command is sent be-
comes busy, disabling the host to control other Reader/Writers. On the other hand, when a Polling
Auto command is sent instead, the Reader/Writer returns a response according to the request from
the host. The communications line with the host will not remain busy, allowing the host to send a
command to other Reader/Writers. During the execution of the Polling Auto command, commands
other than the Polling subcommand, Reset and Stop commands are not executed. The following
flowchart shows the case where the Polling Auto Command is sent to 2 Reader/Writers.
(1) The host sends the Polling Auto
Command to the Node 1
Reader/Writer.
(2) Immediately after command reception,
Node 1 returns a response indicating
the acceptance of the command.
(3) The host sends the Polling Auto
Command to Node 2.
(4) Immediately after command reception,
Node 2 returns a response indicating
acceptance of the command.
(5) The host inquires after the progress of
the communications processing or
stops the Polling Auto processing
using the Polling sub command. When
the communications processing is not
yet complete, the Reader/Writer
returns a response indicating
unfinished processing in reply to the
inquiry of the Polling sub command.
(6) The Node 1 communicates with a Tag
entering the communications area.
(7) Node 1 returns a response indicating
the results of communications with the
Tag in reply to the Polling
subcommand.
(Tag)
(Reader/Writer)
(Host)
Response
Polling Auto
Command
Node 1
Response
Yet to enter
Node 2
Node 2
Response
Polling
subcommand
Yet to enter
Node 1
Node 1
Yet to enter.
Passing in front of Node
1’s antenna
Referring to Node 1
Response
Yet to enter
Node 2
Yet to enter
Referring to Node 2
Communications
processing
Tag
Response
Communications
processing by Node 1 is
complete.
Referring to Node 1
Polling Auto
Command
Polling
subcommand
Polling
subcommand