Omron CS1W-ETN21

Ethernet Unit Function Guide Section 1-1

Reference SECTION 6 FINS Communications

Exchanging Data between OMRON PLCs using Ethernet

Connecting within the

Same Segment Use the UDP/IP version of the FINS communications service (i.e., FINS/

UDP), and construct applications using the SEND(090), RECV(09 8), and

CMND(490) instructions in the ladder program. FINS/UDP is suppor ted by

many OMRON products, and is compatible with earlier Ethernet Units (CS1W-

ETN01/ETN11 and CJ1W-ETN11). The protocol processing for FINS/UDP is

simpler than for FINS/TCP, giving FINS/UDP certain advantages in terms of

performance. Another feature of FINS/UDP is that it can be used for broad-

casting.

On the other hand, with FINS/UDP it is necessary to provide mea sures, such

as retries, for handling communications errors.

Connecting through

Multiple Segments Use the TCP/IP version of the FINS communications service (i.e., FINS/TCP),

and construct applications using the SEND(090), RECV(098), an d

CMND(490) instructions in the ladder program. FINS/TCP is the in itial func-

tion supported by this Ethernet Unit (CS1W-ETN21 and CJ1W-ETN21). It pro-

vides automatic recovery at the TCP/IP layer from communications errors

(such as packet loss) that occur during multilevel routing.

Connecting through multiple segments, such as over the Internet:

Use FINS/TCP.

CX-Programmer

FINS

Internet

IP router

Firewall (Server room)

Intranet

(Office floor)

CX-Programmer

FINS

Connecting from a computer with a dynamic private IP address:

Use FINS/TCP or FINS/UDP.

EthernetEthernet Router

Router

(Production line) CX-Programmer

CX-Programmer

Ethernet

Connecting within the same segment:

Use FINS/UDP.

Ethernet Unit Ethernet Unit

PLC Wireless

FINS

Using media with unreliable

connections, such as wireless

LAN: Use FINS/TCP.

FINS