Product Core Brief

• Model: -CD / -EH
• Brand: GE Fanuc / Emerson Automation
• Series: PACSystems RX3i
• Core Function: High-performance hot standby redundant CPU (Redundancy Processor Unit). Supports primary/backup CPU synchronization, seamless failover for critical control systems. Requires paired redundancy memory module IC695RMX128 / IC695RMX228.
• Product Type: RX3i Hot Standby Redundant CPU (Occupies 2 consecutive backplane slots)
• Key Specs: 1 GHz Celeron M | 64MB Battery-backed RAM + 64MB Flash | Dual serial ports | Supports RX3i PCI + Series 90-30 serial expansion bus Note: Discontinued legacy high-end RX3i CPU; new original stock limited, surplus & refurbished widely available. -CD / -EH = PCB hardware revision suffixes, mechanically plug-compatible. The CPU module itself DOES NOT support hot swap; standard I/O modules support hot-swap on certified baseplates. No onboard Ethernet; Ethernet communication requires IC695ETM001.

 

Key Technical Specifications

• Processor: 1 GHz Intel Celeron M
• Logic Execution: Supports LD, FBD, ST, IL, C program blocks
• Memory
  • 64 MB Battery-backed RAM (ECC error correction)
  • 64 MB Non-volatile Flash memory
  • Max 512 program blocks; single block up to 128 KB
• I/O Tag Capacity
  • Discrete: 32K %I / 32K %Q
  • Analog: Configurable up to 32K %AI / 32K %AQ
• Onboard Serial Interfaces
  • COM1: RS232 D-Sub
  • COM2: RS485 D-Sub
  • Protocols: SNP/SNPX, Modbus RTU Master/Slave, Serial I/O
• Redundancy Characteristics
  • Failover switchover time: Min 3.133 ms, Max ≤1 logic scan
  • Synchronization: Via IC695RMX128/228 fiber/copper redundancy link
• Backplane Bus: Dual bus architecture
  • Native RX3i high-speed PCI backplane
  • Serial expansion bus compatible with Series 90-30 I/O via IC695LRE001
• Power Consumption
  • 3.3 VDC: 1.0 A
  • 5 VDC: 1.2 A
• RTC: Battery-backed real-time clock
• Required Battery: IC695ACC302 Smart Lithium Battery for RAM retention
• Status LEDs: CPU OK, RUN, OUTPUTS ENABLED, FORCE, SYS FLT, COM1 / COM2 activity
• Operating Temperature: 0°C ~ +60°C horizontal cabinet mounting
• Storage Temperature: -40°C ~ +85°C
• Form Factor: Dual-width RX3i module (occupies two adjacent slots)
• Compatible Baseplates: IC695CHS012, IC695CHS016 universal RX3i racks
• Supported Software: Proficy Machine Edition
• Agency Certifications: UL508, Class I Div.2, CE

 

Product Introduction

is the flagship hot standby redundant CPU for PACSystems RX3i platform, designed for high-availability critical applications (power, oil & gas, water treatment, continuous process).

Two CRU320 CPUs form primary/backup redundant pair. The redundancy memory module (RMX128/RMX228) continuously synchronizes all logic states, I/O data and register values between primary and standby. If the master CPU faults, the standby controller takes over control seamlessly with minimal process interruption.

Unique dual-bus design allows mixing modern RX3i I/O on the main rack and legacy Series 90-30 I/O on serial expansion racks, enabling incremental plant migration.

Important Notes:

1. No built-in Ethernet; network communication must use IC695ETM001 installed in adjacent slot.
2. Cannot operate as standalone single CPU without redundancy architecture.
3. Module occupies two consecutive slots; cannot split across baseplate gaps.

 

QA & Testing SOP (Transparency Building)

1. Incoming Inspection: Verify part marking and suffix (-CD / -EH). Inspect backplane gold pins for bending/corrosion; check RS232/RS485 D-Sub connectors and housing integrity.
2. Live Testing: Mount on validated RX3i baseplate. Load user program, test serial Modbus/SNP communication. When available, pair with RMX module to verify redundancy synchronization and simulated failover. Run continuous 24-hour scan test.
3. Electrical Testing: Monitor backplane 3.3V/5V rail stability. Insulation resistance ≥10MΩ between serial field terminals and chassis ground.
4. Firmware Documentation: Record onboard firmware revision; photograph front panel labels before clearing resident program/data.
5. Final QC & Packaging: Place module inside anti-static shielding. Attach dated QC test tag confirming logic execution and serial communication validation prior to shipment.

 

Installation Pitfalls & Guide

❗ No Hot Swap for CRU320 CPU: The dual-slot CPU module cannot be hot swapped. Full rack power shutdown is mandatory before removal. ❗ Dual Slot Occupancy: Must occupy two consecutive empty slots. Do not install single-width modules between the two slots allocated for CRU320. ❗ Redundancy Hardware Mandate: Redundant system requires matching pair of CRU320 + IC695RMX128/RMX228. Missing RMX module disables hot standby synchronization. ❗ Ethernet Module Slot Rule: If using IC695ETM001, ensure proper slot arrangement and avoid occupying required CPU redundancy slots. ❗ Battery Maintenance: Use IC695ACC302 smart battery. Loss of battery power erases retentive memory and RTC after power cycle. ❗ Revision Interchange: -CD and -EH are mechanically interchangeable. After replacement, verify firmware compatibility and complete redundancy synchronization testing. ❗ ESD Risk: Static discharge damages serial transceivers and backplane interface circuits, causing intermittent communication failures.

Replacement Guide

1. Pre-install: Lockout-tagout rack power; back up full PLC project. Photograph slot layout, serial wiring and redundancy link cabling. Record battery status.
2. Removal: Disconnect serial cables; unlatch dual-slot CPU and slide straight out without twisting backplane pins.
3. Install: Seat new into the original two consecutive slots, reconnect serial and redundancy link wiring. Confirm battery connection.
4. Power-on Test: Restore rack power; confirm CPU OK/RUN LED status, download project, verify serial communication. For redundant systems, test primary-to-standby failover function.

 

FAQ

Q: Does -CD/EH support hot swapping? A: No. The CPU itself cannot be hot swapped. Standard RX3i I/O modules support hot-swap on certified baseplates.

Q: What is the difference between -CD and -EH revision suffix? A: Base model core functionality is identical. -CD / -EH denote different PCB hardware revisions. Mechanically plug-compatible; always verify firmware compatibility and perform full redundancy testing after substitution.

Q: Can run as a single non-redundant CPU? A: Hardware allows single operation, but it is engineered for hot standby architecture. For non-redundant systems, standard IC695CPU320 is recommended.

Q: What is the difference between and IC695CPU320? A:

• : Dual-slot, built-in hardware support for hot standby redundancy, requires RMX synchronization module.
• IC695CPU320: Single-slot standard CPU, does not support full hot standby redundancy. They are not interchangeable.

Q: Can this CPU connect Series 90-30 I/O modules? A: Yes, via IC695LRE001 serial expansion transceiver on remote racks. IC693 modules cannot be inserted directly into RX3i main baseplate.

Q: Does CRU320 have built-in Ethernet port? A: No. Ethernet communication requires separate IC695ETM001 module.

Q: Will the PLC program automatically work on a replacement CRU320? A: Program code is portable, but redundant system parameters, serial port configurations need verification. Redundancy synchronization must be revalidated after replacement.

Q: What happens during CPU failover? A: All synchronized %I/%Q/%AI/%AQ and register data are maintained. Outputs switch seamlessly; switchover time depends on logic scan cycle (minimum ~3.133ms).