PACSystems* RX3i Redundancy CPU – Overview

The PACSystems RX3i Redundancy CPU is designed for real-time control of machines, industrial processes, and material handling systems. It supports hot standby (HSB) redundancy, ensuring high system availability and fault tolerance in critical automation applications.

The CPU communicates with programming software and HMI devices via serial communication using the SNP Slave protocol, and interfaces with I/O and intelligent option modules through a dual backplane architecture.

Dual Backplane Architecture

The RX3i Redundancy CPU uses a dual backplane bus to support both legacy and advanced I/O:

High-speed PCI backplane
Enables high-throughput communication with advanced RX3i I/O modules.

Serial backplane
Provides backward compatibility with existing Series 90-30 I/O, simplifying system migration and upgrades.

Redundancy Features

Hot Standby (HSB) redundancy architecture

A redundancy system consists of:

Two Redundancy CPUs (IC695CRU320)

Two Redundancy Memory Xchange (RMX) modules
(IC695RMX128 or IC695RMX228), configured as a redundancy link

Automatic synchronization of application code and data between CPUs

Seamless switchover in the event of a primary CPU failure

Memory and Data Handling

64 MB battery-backed user RAM

64 MB non-volatile Flash user memory

Access to bulk memory via %W reference table

Configurable allocation of program and data memory

Support for auto-located symbolic variables, allowing flexible memory usage

Programming Capabilities

Supported programming languages:

Ladder Diagram (LD)

Structured Text (ST)

Function Block Diagram (FBD)

Supports up to 512 program blocks

Maximum program block size: 128 KB

Reference table capacity:

32 Kbits each for discrete inputs (%I) and outputs (%Q)

Up to 32 K words each for analog inputs (%AI) and outputs (%AQ)

I/O and System Expansion

Compatible with most Series 90-30 I/O modules

Supports expansion racks

Supports a wide range of:

I/O modules

Communication modules

Motion and intelligent modules

Refer to PACSystems RX3i System Manual (GFK-2314F or later) for the complete compatibility list

Communication Interfaces

Two onboard serial ports:

RS-485

RS-232

Ethernet communication via rack-mounted Ethernet Interface module
(IC695ETM001)

Supports SNTP time synchronization over Ethernet (Ethernet Release 5.0 or later)

Firmware and Maintenance

CPU firmware can be upgraded in the field

Supports firmware upgrades for backplane modules

Designed for long-term maintainability and system scalability

Compliance

Compliant with EU RoHS Directive 2002/95/EC

Applicable exemptions: 7(a), 7(c)-I, and 7(c)-III