Omron CS1W-ETN21 - Manual (Page 29)

4
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(098), and
CMND(490) instructions in the ladder program. FINS/UDP is supported 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 measures, 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), and
CMND(490) instructions in the ladder program. FINS/TCP is the initial 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.
Ethernet Ethernet
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