204
FINS/TCP Method Section 8-3
FINS/TCP Connection Status (Word n+24)
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 a communications error or a FINS command (i.e., FINS/TCP CON-
NECTION REMOTE NODE CHANGE REQUEST).
Note The starting word of the FINS/TCP Connection Status Area is different in the
CS1W-ETN21 and CJ1W-ETN21 Ethernet Units; it is n+23 in the Ethernet
Units. If a ladder program using FINS/TCP communications was created for
Ethernet Units, and is being reused for EtherNet/IP Units and built-in Ether-
Net/IP ports, change the word starting word address for this area from n+23 to
n+24.
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, and to manage 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) is sent by the client.
• When there is no response from the client when the keep-alive function is
in effect.
15 14 13 12 11 10 09 07 06 05 04 03 02 01 00
n+24
*: Bit 15 corresponds to connection No. 16, bit 00 to connection No. 1, etc.
08
Connection request (C→S)
FINS node number A sent
Ethernet/IP Unit
(Server)
Passive open
Connection established
Local node No. sent
FINS frame sent
Personal computer
(Client)
Active open
Local node No. sent
Connection established
Remote node No. received
FINS node number B sent
FINS node numbers exchanged
Connection established
Normal data communications
Remote node No. received
FINS frame sent
Full duplex communications
Example:
IP address C
FINS node number A
Example:
IP address S
FINS node number B
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