Omron CS CJ1W-ETN21 Operation Manual page 204

FINS/TCP Method
Connection Sequence
Normal Operation
180
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.)
Header
Length
FINS/TCP header
Command
Reserve
The details of the above frame are shown in the following table.
Item Contents (hexadecimal)
Header 46494E53
Length 00000008
Command 00000006
Error code 00000000
Client
SYN
connect
SYN, ACK
ACK
A
send
ACK
D
recv
ACK
F
recv
ACK
E
send
ACK
Size
(bytes)
4
4
4
4
Server
accept
B
recv
Normal
C
send
E
send
connect
F
recv
Message from host layer
Section 7-4
Remarks
ASCII code: 'FINS'
8 bytes: Length of data after
command.
Not used, so does not require
checking at the receiving end
(client).
Socket interface
Message from TCP/IP layer