Omron CS CJ1W-ETN21 - Manual (Page 204)

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FINS/TCP Method Section 7-4
After the command is sent, if ACK is returned in the TCP layer by the remote
node, the connection that is established is maintained. If RST is returned in
the TCP layer by the remote node, the established connection is closed.
If the FINS NODE ADDRESS DATA SEND (CLIENT TO SERVER) or FINS
NODE ADDRESS DATA SEND (SERVER TO CLIENT) command is received
after a connection has already been established as a FINS/TCP client and
server, the error code (00000003 hexadecimal: command not supported) will
be sent in the FINS FRAME SEND ERROR NOTIFICATION command, and
the connection will be terminated.
The error code (00000021 hexadecimal: specified node already connected)
will be sent using an FINS NODE ADDRESS DATA SEND (SERVER TO CLI-
ENT) command to the connected node that received FINS NODE ADDRESS
DATA SEND (CLIENT TO SERVER) from the client with the same FINS node
address as the currently open connection, regardless of the result. Do not
send this command from the client. (The error code (00000003 hexadecimal:
command not supported) will be sent in the FINS FRAME SEND ERROR
NOTIFICATION command, and the connection will be terminated.)
The details of the above frame are shown in the following table.
Connection Sequence
Normal Operation
Item Contents (hexadecimal) Remarks
Header 46494E53 ASCII code: ‘FINS’
Length 00000008 8 bytes: Length of data after
command.
Command 00000006
Error code 00000000 Not used, so does not require
checking at the receiving end
(client).
Size
(bytes)
4
4
4
4
FINS/TCP header
Header
Length
Command
Reserve
connect
connect
send
recv
accept
recv
send
SYN
SYN, ACK
ACK
ACK
ACK
recv
send
send
recv
ACK
ACK
Client Server
Normal
Socket interface
Message from TCP/IP layer
Message from host layer
A
B
C
D
E
F
E
F