Omron CS CJ1W-ETN21 Operation Manual page 197

FINS/TCP Method
FINS/TCP Connection
Status (Word n+23)
FINS/TCP
Communications
Procedure
Personal computer
Example:
IP address C
FINS node address A
Active open
Connection established
Local node address sent
Remote node address received
FINS frame sent
While a connection with a remote node is established, the bit corresponding to
the FINS/TCP connection status turns ON in the section of the CPU Bus Unit
words allocated in the CIO Area. The bit turns OFF if the connection is termi-
nated by an error in communications with a remote node or a FINS command
(i.e., FINS/TCP CONNECTION REMOTE NODE CHANGE REQUEST).
15 14 13 12 11 10 09
n+23
*: Bit 15 corresponds to connection No. 16, bit 00 to connection No. 1, etc.
With FINS/TCP, FINS node addresses are exchanged immediately after a
connection is established. This makes it possible to determine the FINS node
addresses to which the 16 connection numbers are connected, and to man-
age them in an internal table.
(Client)
Connection request (C→S)
FINS node address A sent
FINS node address B sent
Full duplex communications
After a connection has been established as a FINS/TCP server, it is termi-
nated in the following ways.
• When the connection is closed by the client.
• When a FINS command to close the connection (FINS/TCP CONNEC-
TION REMOTE NODE CHANGE REQUEST: command code 27 30 hexa-
decimal) is sent by the client.
• When there is no response from the client when the keep-alive function is
in effect.
• If a command other than FINS FRAME SEND is received from the client,
the connection will close after the FINS FRAME SEND ERROR NOTIFI-
CATION command is sent.
After a connection has been established as a FINS/TCP client, it can be termi-
nated in the following ways.
• If the connection is closed by the server.
08 07 06 05 04 03 02 01 00
Ethernet Unit
(Server)
Example:
IP address S
FINS node address B
Passive open
Connection established
Remote node address received
Local node address sent
FINS frame sent
Section 7-4
Connection established
FINS node addresses
exchanged
Normal data communications
173