Omron CP1L-EL20DR-D, Operation Manual

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Socket Services Section 6-6
6-6-3 Socket Services and Socket Status
When using socket services, it is important to consider the timing of the status
changes in the Socket Status Area. The diagram below shows a flowchart for
opening UDP. The flow is similar for other socket services. Replace the names
of the appropriate flags in the flowchart to adapt it to other socket services.
Note For details about timing charts, refer to SECTION 6 Socket Services in the
Ethernet Units Construction of Applications Operation Manual (Cat. No.
W421-E1).
Socket services cannot support CMND command.
Check TCP Connection/UDP Open Flag. The specified UDP socket is
already open.
Turn ON UDP Open Request Switch.
Start UDP Open.
OFF?
Program Flow
Is Bit 15 (Open Flag) in the socket status word for
the socket being used OFF?
(Checks to see if the socket is open before com-
munications and close processing.)
YES
Error Evaluation
UDP socket opened.
NO
This Socket Service Request Switch is used to request
opening of a UDP socket to the Ethernet Unit.
Confirm end of processing.
0000?
YES
NO
ON/OFF?
OFF
This Socket Service Request Switch that was turned
ON will be turned OFF by the Ethernet Unit when
processing has been completed.
Check response code.
Is the response code 0000, indicating a normal end?
An error occurred. The specified
socket could not be opened.