Omron CJ1W-EIP21 User Manual

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).

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.

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