Fins/tcp communications procedure – Omron CS CJ1W-ETN21 User Manual
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FINS/TCP Method
Section 7-4
FINS/TCP Connection
Status (Word n+23)
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).
FINS/TCP
Communications
Procedure
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.
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.
15
14
13
12
11
10
09
07
06
05 04
03
02
01
00
n+23
*: Bit 15 corresponds to connection No. 16, bit 00 to connection No. 1, etc.
08
Connection request (C
→S)
FINS node address A sent
Ethernet Unit
(Server)
Passive open
Connection established
Local node address sent
FINS frame sent
Personal computer
(Client)
Active open
Local node address sent
Connection established
Remote node address received
FINS node address B sent
FINS node addresses
exchanged
Connection established
Normal data communications
Remote node address received
FINS frame sent
Full duplex communications
Example:
IP address C
FINS node address A
Example:
IP address S
FINS node address B