Omron CS CJ1W-ETN21 - Manual (Page 205)

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FINS/TCP Method Section 7-4
1,2,3... 1. After the TCP connection is established, the client node address is sent by
the client to the server using the FINS NODE ADDRESS DATA SEND (CLI-
ENT TO SERVER) command.
2. The client’s FINS node address (client node address) is obtained from the
received command.
3. The server’s node address is sent by the server to the client using the FINS
NODE ADDRESS DATA SEND (SERVER TO CLIENT) command.
4. The server’s FINS node address is obtained from the received command.
5. The FINS message is sent using the FINS FRAME SEND command.
6. The FINS message is separated out from the received command.
Note In steps 5 and 6 both the client and server can send and receive FINS mes-
sages (commands/responses) in both directions.
Error Connection
Sequence
1,2,3... 1. The client sends the FINS NODE ADDRESS DATA SEND (CLIENT TO
SERVER) command to the server.
2. The received command is decoded (e.g., if an error occurs, the code that
is not ‘FINS’ (ASCII code) in the command header is stored.)
3. The server sends the error code for the detected error (in this example,
00000001 hexadecimal: Header is not ‘FINS’ (ASCII code)) in the FINS
NODE ADDRESS DATA SEND (SERVER TO CLIENT) command to the
client, and the TCP/IP port is closed.
4. The error code for the received command is decoded, and the TCP/IP port
is closed.
Client Server
Error
Socket interface
Message from TCP/IP layer
Message from host layer
A
B
C
D
SYN
SYN, ACK
ACK
ACK
ACK
FIN
FIN
ACK
connect
connect
send
recv
close
accept
recv
send
close
Connection closed
according to TCP/IP
protocol procedure.