Tcp Close Request; Instruction) - Toshiba V Series User Manual

6.4.8 TCP close request (using the USEND_T instruction)
(1) Function
Close the open TCP socket.
Release the (unlimited wait state) receive request and terminate the TCP socket.
(2) Request command structure and error status
<Request command>
CMD
CMD+1
CMD+2
<Error status>
STATUS
Error status examples
Error status number
-5004(16#EC74)
2912(16#B60)
2945(16#B81)
(3) Important notes
• TCP close requests are processed with the highest priority and other executing
requests are discarded, even if the object socket is executing a TCP open, send, or
receive request. Other requests during the execution of this request will be discarded.
• An error is returned if a close request is issued for a socket that is not yet opened.
Error status: Socket unopened ••• 2945(16#B81)
• An error is returned if a value other than 1 to 8 is specified as the socket identifier.
Error status: Invalid socket identifier ••• 2946(16#B82)
• A TCP receive requests will result in an error being returned if an unlimited wait state
TCP open request/receive request is terminated with this request.
Error status: Transmission completion timeout ••• 5002(16#EC76)
Supplemental Remarks
The S controller sees its requests (module control and socket interface transmission) to the
EN311 as being "transmission" requests. As a result, when a request is forcibly terminated and
a response is not received from the EN311, the result is a send request timeout even if the
instruction was a "receive request".
• If the S controller issues the TCP close request to the EN311, the EN311 sends the
connection end request (FIN) at the TCP level to the remote node. At this stage, the
EN311 replies the completion of the close request to the S controller.
6F8C0904
F
Request destination EN311 module slot number
Command (16#0339)
Socket identifier
F
Socket identifier (1-8) or Error status
Destination EN311 module slot number is missing or socket identifier is out
of range
Transmission disabled
Socket not opened yet
6.4 Using the EN311 Socket Interface
0
Value:1-8
0
Description
6
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