6 F 3 B 0 3 6 2
8.TCP close request (using the SEND instruction)
a.Function
Close the open TCP socket.
Release the (unlimited wait state) receive request and terminate the TCP socket.
b.Transfer parameters
A A+1 A+2
3100H
CMD = 0039H
SportNO
Module designation Command number Socket identifier (1 to 8)
c.Status (See figure 4.3 for details on bits C, D, E and F.)
B B+1
F E D C B A 9 8 7 6 5 4 3 2 1 0
|
|
|
| SportNO | TermSTS |
Detailed information (Only valid when TermSTS = 0BH.)
SportNO: Socket identifier (1 to 8)
TermSTS: See tables 4.3 and 4.4.
Detail information: See table 4.5.
d.Important items
∙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.
Status: Transmission error (TermSTS = 0BH)
Detailed information: Unopened (0081H)
∙An error is returned if a value other than 1 to 8 is specified as the socket identifier. Status: Transmission error (TermSTS = 0BH)
Detailed information: Illegal socket identifier (0082H)
∙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.
Status: Transmission completion timeout (TermSTS = 06H)
Supplement:
The T2N sees its requests (module control and socket interface transmission) to the Ethernet Port as being "transmission" requests. As a result, when a request is forcibly terminated and a response is not received from the Ethernet Port, the result is a send request timeout even if the instruction was a RECV instruction.
∙If a close request is comes from the remote port TCP socket while a connection is established, the local port must also close the socket. As a technique for checking for the reception of close requests from the remote TCP socket, user programs should monitor the RCLOSE and CONN bits in the socket status. (See section 6.3.)
⎯ 109 ⎯
