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Communications Methods
Polling Auto Mode
4)
If an Auto command is used when a single host controls more than one Controllers, the com-
munications path between the host and one of the Controllers to which the command is sent
becomes busy, disabling the host to control other Controllers. On the other hand, when a Polling
Auto command is sent instead, the Controller returns a response in reply to a Polling subcom-
mand, which allows the host to send a command to other Controllers. 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 Controllers.
Host
Polling Auto
Command
Node 1
Polling Auto
Command
Node 2
Polling
subcommand
Referring to Node 1
Polling
subcommand
Referring to Node 2
Polling
subcommand
Referring to Node 1
5-40
Controller
Response
Response
Node 2
Response
Node 1
Not approaching yet.
Response
Node 2
Not approaching yet.
Communications
processing
Node 1
Response
Communications
processing by Node 1 is
complete.
Tag
Not approaching yet
Not approaching yet
Not approaching yet
Tag
Passing in front of Node
1's antenna
1)
The host sends the Polling Auto
Command to the Node 1 Controller.
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 Controller 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.
Section 5-5
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