NETWORKING
SNAP PAC R-Series Controller User’s Guide
34
Ethernet Link Redundancy
The following diagram shows two SNAP PAC R-series controllers functioning as I/O unit
brains connected to two separate Ethernet networks. This configuration addresses the
concern that an Ethernet network may fail or need maintenance, leaving the PC running
OptoOPCServer, the PC running PAC Display, the controller, and the I/O units unable to
communicate. The network shown in this diagram requires PAC Control Professional, PAC
Display Professional, and OptoDataLink.
In this configuration, if one network goes down, devices can still communicate because the
SNAP PAC S-series controller and the SNAP PAC R-series controllers both have two network
interfaces, and each PC in this system has two network interface cards.
NOTE: If you need controller redundancy (two controllers running concurrently, with one able to
take over if the other fails), use SNAP PAC S-series standalone controllers with the PAC
Redundancy Option Kit and PAC Control Professional. For more information, see the Opto 22
website.
PC with two NICs running
PAC Display Professional
PC with two NICs running
OptoOPCServer
I/O units are all connected by the controller.
Each I/O unit is connected to its own group of
sensors and actuators, but all are connected to
the same two networks.
SNAP PAC S-series
controller controls
all I/O units.
SNAP PAC R-series
controller
Sensors & actuators,
location #2
Sensors & actuators,
location #1
Opto 22 Redundant Network
Ethernet switch,
network #2
Ethernet switch,
network #1
SNAP PAC R-series
controller
