
147
6
F
3
B
0
3
6
2
RCLOSE
NOACK
CONN
RCV
8.4 Socket Interface Information
The information for the eight socket interface sockets held by the Ethernet Port can be read out
with the T2N READ instruction. (See Section 6.3 Socket Interface Information.) The Ethernet Port
holds five words of socket status information for each socket.
•
Remote port TCP/UDP port number
•
Remote port IP address
•
TCP/UDP port number for this socket
•
Socket status
Table 8.7 lists the structure of the socket interface information and the extended memory area
addresses.
Table 8.7 Socket Interface Information
Socket identifier
1
2
3
4
5
6
7
8
Remote port number (TCP only)
0F4BH
0F53H
0F5BH 0F63H 0F6BH 0F73H
0F7BH 0F83H
Remote port IP address (TCP only)
0F4CH
0F4DH
0F54H
0F55H
0F5CH
0F5DH
0F64H
0F65H
0F6CH
0F6DH
0F74H
0F75H
0F7CH
0F7DH
0F84H
0F85H
Local port TCP/UDP port number
0F4EH
0F56H
0F5EH 0F66H 0F6EH 0F76H
0F7EH 0F86H
Socket status
0F4FH
0F57H
0F5FH
0F67H 0F6FH
0F77H
0F7FH 0F87H
For UDP sockets, the remote port number and IP address data are invalid.
The socket status has the following structure.
F
E
D
C
B
A
9
8
7
6
5
4
3
2
1
0
Bit no. Bit
Condition under which the bit is set to 1
Condition under which the bit is reset to 0
F
TCP
TCP used by the socket
The socket closed in response to a close request
E
UDP
UDP used by the socket
The socket closed in response to a close request
D
AOPEN TCP socket in active open state
The socket closed in response to a close request
C
POPEN TCP socket in passive open state or UDP
socket in open state
The socket closed in response to a close request
B
CONN
TCP connection established
Disconnected by the local port with a close request
Disconnected by the remote port
A
RCV
Received text present
No received text
9
RCLOS
E
An established TCP connection disconnected
by the remote port
The socket closed in response to a close request
8
NOACK No response received from the remote port for
a local port send operation in a state where a
TCP connection was established, and the TCP
resend function resulted in a timeout (because
the remote port was down, etc.).
The socket closed in response to a close request
If the wait time exceeds the set value during a
TCP active open request.
This state does not occur for TCP passive
open requests.
When a TCP active open request is reissued.
AOPEN
POPEN
TCP
UDP
A socket status in which neither AOPEN nor POPEN is set to 1 indicates that the socket is in the
closed state.