Rockwell Automation Publication 1715-RM001A-EN-P - June 2019
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Using the 1715 I/O
Chapter 3
1715 Redundant I/O
Overview
The 1715 Redundant I/O System lets a ControlLogix SIL 2 controller
communicate to a remote, redundant I/O chassis by using EtherNet/IP. The SIL
2 1715 Redundant I/O system provides fault tolerance and redundancy for
critical processes by using a redundant adapter pair and multiple redundant I/O
modules that have diagnostics and are easily replaceable while the system is
running.
The 1715 Redundant I/O System is a modular system in which the adapter and
I/O base units snap together by using mating connectors and retaining clips to
form the backplane. One module in a duplex pair can be removed and replaced
without system interruption. The base units, via termination assemblies, provide
the interconnections for power, adapter, and I/O data. Once connected, the base
units form the single mechanical assembly or backplane.
The modular architecture lets you build and adapt a system to suit the specific
needs of an installation. The architecture lets you choose from different levels of
I/O fault tolerance. Any of the modules can be used Simplex, Duplex, and/or a
combination of both. For example, there can be redundant adapters, two duplex
input module pairs, a duplex output module pair, and then simplex input and
output modules in the same I/O system. The system is designed to have two
adapters at all times but the system continues to run on one adapter on the
occasion that one adapter faults. The missing module diagnostic cannot be
disabled for this.
The 1715 Redundant I/O System consists of a two-slot adapter base unit that
houses a redundant adapter pair. The adapter base unit is connected to up to
eight I/O base units, which can hold up to 24 I/O modules (three I/O modules
per I/O base unit) when connected together. The I/O modules can be
configured in any combination of simplex or duplex pairs, depending on the
mode of operation needed. The I/O base units can be connected directly to the
adapter base unit and other I/O base units, or through expansion cables.
