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Using Socket Services with CMND(490) Section 6-3
6-3-2 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 program flow-
chart for opening UDP.
Program flow is similar for other socket services. Replace the names of the
appropriate flags in the flowchart to adapt it to other socket services.
An error occurred. The Ethernet
Unit did not receive the UDP
OPEN REQUEST command.
Check socket status.
Start UDP Open
OFF?
ON/OFF
The specified UDP socket is
already open.
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
Check the Port Enabled Flag.
Check response.
Check Opening Flag status.
Check results storage area response code.
ON?
The specified port is running
network communications.
Is the Port Enabled Flag in A502 for communica-
tions port ON?
YES
Use the CMND(490) to send the UDP OPEN RE-
QUEST command (2701) to the Ethernet Unit.
Is the response code = 0000 (normal) for the
UDP OPEN REQUEST command?
Wait until bit 00 in the socket status turns OFF
(open complete).
Is response code = 0000?
0000?
YES
0000?
YES
UDP opened
(Socket status bit 00)
An error occurred. The specified
socket could not be opened.
NO
NO
NO
NO
Execute FINS command (via CMND(490)) for Ethernet Unit.