GE PACSystems RX3i IC695RMX128 – 128 MB Redundancy Memory Xchange for High-Availability Control

The GE PACSystems RX3i IC695RMX128 is a 128 MB Redundancy Memory Xchange (RMX) module designed to keep hot-standby RX3i controller pairs synchronized and ready for seamless switchover. It provides deterministic, high-speed memory mirroring between primary and backup racks so critical processes continue without a bump.

From my experience, this is the module teams pick when they need predictable redundancy behavior across utilities, power, and continuous manufacturing. It’s typically used in systems where seconds (or even milliseconds) matter during failover.

• 128 MB mirrored memory – Large, deterministic data area for controller state, setpoints, and critical variables.

• High-speed redundancy link – Purpose-built channel for fast, reliable primary-to-standby synchronization.

• Deterministic failover behavior – Helps achieve bumpless transfer in hot-standby RX3i architectures, in most cases without data loss.

• Backplane integration – Slot-mounts in an RX3i rack and works alongside redundant CPUs (e.g., IC695CRU-series).

• Diagnostics and status indicators – Front-panel LEDs and accessible diagnostics simplify commissioning and troubleshooting.

• Long-distance link capability – Supports fiber-based inter-rack connections, typically enabling placement in separate control rooms for resilience.

• Engineered for 24/7 operation – Industrial-grade design suited for continuous processes and harsh plant environments.

You’ll typically find the IC695RMX128 in high-availability RX3i systems where any controller switchover has to be smooth and quick:

• Water & wastewater treatment – maintaining stable process control during controller maintenance or fault events.

• Power generation & substations – synchronizing logic and alarms for continuous operations.

• Oil & gas (midstream/refining) – reducing process upsets during failover on critical units.

• Pharma & chemicals – supporting validated, uninterrupted batch and continuous processes.

• Discrete/Hybrid manufacturing – protecting uptime on line control, conveying, and packaging systems.

• Reliability – Deterministic memory mirroring helps deliver consistent switchover behavior under load.

• Compatibility – Designed for PACSystems RX3i redundancy with redundant CPUs (e.g., IC695CRU-series) and standard RX3i racks.

• Lifecycle cost – Minimizes downtime costs; the module is backplane-powered and typically doesn’t require extra power hardware.

• Scalability – 128 MB size supports large applications with room for state data, interlocks, and diagnostics.

• Support ecosystem – Integrates with Proficy Machine Edition for configuration and diagnostics, streamlining engineering effort.

A straightforward setup, but there are a few best practices that tend to save time on site:

• Rack placement – Install one IC695RMX128 in each redundant RX3i rack. Maintain adequate ventilation; most panels follow IEC enclosure standards with forced air when ambient runs warm.

• Fiber routing – Use quality fiber patch cords, keep bend radius within spec, and route primary and backup fibers on separate paths when possible for resilience.

• Grounding & EMC – Proper panel grounding, shield termination, and clean cable segregation (power vs. signal) improve link stability.

• Wiring practices – De-energize racks before module insertion unless your validated procedure and redundancy design allow online replacement; follow ESD precautions.

• Routine maintenance – Inspect and clean fiber connectors, verify redundancy status LEDs, back up configuration, and keep module/CPU firmware at approved versions.

• Commissioning tip – Perform controlled failover tests during SAT; you might notice issues earlier if network time sync or alarms aren’t mirrored as expected.

• CE and UL/cUL compliance for industrial control equipment (typical for PACSystems RX3i hardware).

• RoHS-conformant materials.

• Manufactured under ISO 9001 quality systems.

• Manufacturer’s limited warranty, commonly 2 years (can vary by region and channel).

• IC695CRU320/IC695CRU321 – RX3i redundant CPUs commonly paired with the IC695RMX128.

• IC695CHS0xx series – RX3i racks/chassis for module installation.

• IC695PSxxx – RX3i power supplies sized to your rack load.

• IC695ETM001 / IC695PNC001 – Ethernet or PROFINET modules if you’re building a fully redundant networked architecture.