CHAPTER 1: OVERVIEW
SNAP PAC S-Series User’s Guide
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Ethernet Link Redundancy
The following diagram shows a SNAP PAC S-series controller connected to two separate Ethernet
network links. 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. In this configuration, if one link goes down, devices can still
communicate on the other. Each PC has two network interface cards (NICs), and the SNAP PAC
S-series controller and the I/O units (SNAP-PAC-R1 and -R2 controllers) have two network interfaces
as well.
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 and actuators,
location #2
Sensors and actuators,
location #1
Opto 22 Redundant Network
Ethernet switch,
network #2
Ethernet switch,
network #1
SNAP PAC R-series
controller
