Omron CJ1W-ETN21 - 04-2009 Operation Manual page 29

Ethernet Unit Function Guide
Connecting through multiple segments, such as over the Internet:
Use FINS/TCP.
CX-Programmer
FINS
IP router
Firewall
Router
Reference
Exchanging Data between OMRON PLCs using Ethernet
Connecting within the
Same Segment
Connecting through
Multiple Segments
4
Internet
Intranet
(Server room) (Office floor)
CX-Programmer
DNS server
POP3 server
SMTP server
SNTP server
Ethernet
Router
(Production line)
Ethernet
Ethernet Unit
SECTION 6 FINS Communications
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.
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 from a computer with a dynamic private IP address:
Use FINS/TCP or FINS/UDP.
FINS
Ethernet
Connecting within the same segment:
CX-Programmer
Use FINS/UDP.
FINS
Ethernet Unit
PLC
Wireless
FINS
Section 1-1
CX-Programmer
Using media with unreliable
connections, such as wireless
LAN: Use FINS/TCP.