GE IC695CPE310 PLC CPU Module – PACSystems RX3i

GE IC695CPE310: Backplane Bus Architecture and Deterministic Scan Execution in PACSystems RX3i

The IC695CPE310 is the primary Central Processing Unit of GE’s PACSystems RX3i platform, a control architecture built on a 32-bit PCI backplane bus capable of sustained throughput up to 200 MB/s. Unlike earlier GE CPU families that relied on proprietary serial backplane protocols, the RX3i PCI bus allows the IC695CPE310 to service multiple I/O modules, intelligent option modules, and motion controllers within a single deterministic scan window — without the inter-rack latency penalties that characterize VME or ISA-based predecessors.

The CPU occupies Slot 0 of the RX3i main rack (IC695CHS012 or IC695CHS016) and arbitrates all backplane transactions. On power-up, the IC695CPE310 executes a structured initialization sequence: POST (Power-On Self-Test) validates internal SRAM integrity, flash memory checksums, and Ethernet PHY link states before the CPU transitions to STOP or RUN mode depending on the stored configuration. This initialization architecture ensures that no partial or corrupted program state can propagate to field outputs — a critical requirement in process control and safety-adjacent applications.

With 10 MB of unified user memory — a single pool shared between program logic and data tables — the IC695CPE310 eliminates the fixed memory partitioning that constrained earlier GE Series 90-70 CPUs. Engineers can allocate memory dynamically across large ladder programs, structured text routines, and extensive data registers without pre-configuring segment boundaries. This unified model also simplifies firmware-level memory management, reducing the risk of fragmentation-induced scan time variability in long-running applications.

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Technical Parameters

Hardware Logical Analysis

The IC695CPE310’s PCI backplane arbitration model assigns bus mastership to the CPU for all non-DMA transactions. Intelligent option modules — such as the IC695ETM001 Ethernet module or IC695PBM300 PROFIBUS master — operate as PCI bus targets, responding to CPU-initiated read/write cycles. This master-target topology prevents bus contention and guarantees that the CPU retains scan-cycle determinism even when multiple communication modules are simultaneously active.

From an EMC standpoint, the RX3i backplane PCB employs a multi-layer ground plane strategy. Signal traces are routed on inner layers sandwiched between dedicated power and ground planes, reducing radiated emissions and improving immunity to conducted interference per EN 61000-4-4 (EFT/Burst) and EN 61000-4-5 (Surge) test standards. The IC695CPE310’s front-panel connectors — USB, RS-232, and dual RJ-45 — incorporate transient voltage suppression (TVS) diodes and common-mode chokes to clamp electrostatic discharge events to safe levels before they reach the CPU’s internal logic.

Program retention is handled by a two-tier non-volatile architecture. The user program is stored in internal NOR flash memory (endurance: >100,000 write cycles), which is immune to power loss without any battery. Retentive data — timer accumulators, counter values, and user-designated %R registers — are maintained by a supercapacitor-backed SRAM array. The supercapacitor provides approximately 72 hours of data retention at 25 °C after a complete power loss, eliminating the battery replacement maintenance cycle common in older GE Series 90-30 CPUs.

The dual Ethernet ports share a single MAC controller but present independent PHY interfaces, each with its own MAC address and IP stack. This architecture allows Port 1 to carry SRTP (Service Request Transport Protocol) traffic to SCADA/HMI systems on the plant LAN while Port 2 simultaneously handles CPU-to-CPU peer communications on an isolated control network — with no shared buffer contention between the two traffic streams.

System Integration Benefits

• Deterministic PCI Bus Scan: The 200 MB/s PCI backplane eliminates the inter-module polling delays inherent in serial backplane designs, delivering consistent sub-millisecond I/O update latency across all rack slots regardless of module count.
• Dual Independent Ethernet for Network Segmentation: Separate IP stacks on Port 1 and Port 2 allow simultaneous SCADA/HMI connectivity and peer CPU communication without VLAN configuration or managed switch dependency — simplifying network architecture in greenfield installations.
• Unified 10 MB Memory Pool: Eliminates fixed program/data memory partitioning, allowing engineers to allocate the full memory space to program logic, data registers, or any combination — without recompiling or reconfiguring memory maps when application scope changes.
• IEC 61131-3 Multi-Language Project Support: A single PME project can contain LD, FBD, ST, and SFC program blocks simultaneously, enabling teams to apply the most appropriate language to each control task — sequential logic in LD, analog PID loops in FBD, complex algorithms in ST — without cross-project data mapping overhead.
• USB Direct Programming Port: Eliminates the RS-232-to-USB adapter requirement that complicated field commissioning on earlier GE CPUs. A standard USB Type-B cable connects directly to any laptop, reducing commissioning tool inventory and eliminating adapter-induced communication errors.
• Hot-Standby CPU Redundancy: When paired with the IC695RMX128 Redundancy Memory Xchange module, the IC695CPE310 supports bumpless switchover to a standby CPU with memory synchronization latency below one scan cycle — meeting the availability requirements of continuous process applications.
• Backward I/O Compatibility with Series 90-30: Legacy IC694 I/O modules can be mounted in RX3i expansion racks via adapter backplanes, preserving existing field wiring and I/O module investments during platform migration — a measurable reduction in migration capital expenditure.
• Embedded Diagnostics Transparency: The IC695CPE310 maintains a fault table accessible via PME that logs CPU faults, I/O module faults, and communication errors with timestamp resolution to the millisecond. This fault log persists across power cycles in flash memory, providing post-mortem diagnostic data without requiring an external data logger.
• Field Firmware Upgrade Without Rack Removal: Firmware updates are applied via USB or Ethernet using PME’s firmware upgrade utility while the module remains seated in the rack. The upgrade process includes automatic checksum verification and rollback capability if the new firmware image fails integrity validation.
• Proficy Machine Edition Software Ecosystem: Full integration with PME enables online program editing (logic changes without stopping the CPU), force tables for I/O commissioning, data logging to historian, and motion coordination for multi-axis servo applications — all within a single engineering environment.

Quality Assurance & Global Logistics

Every IC695CPE310 unit offered through siemensplc.com is sourced from verified supply channels including authorized GE distributors, decommissioned OEM production lines, and audited surplus inventories. Each unit undergoes a structured pre-shipment inspection protocol: visual examination of PCB surfaces, connector pin integrity, and label authenticity; power-on self-test (POST) execution with pass/fail logging; Ethernet port link-state verification; and firmware version confirmation against GE’s published release matrix.

Units are cross-referenced against GE Fanuc serial number databases where accessible. Any unit that cannot be positively verified is quarantined and excluded from inventory — it is not listed, discounted, or offered as an alternative. This zero-tolerance counterfeit policy is enforced at the receiving inspection stage, not at the point of customer complaint.

Shipments originate from our warehouse in Xiamen, China. Xiamen’s port infrastructure and proximity to major international freight hubs — including Xiamen Gaoqi International Airport — supports next-flight-out dispatch for urgent orders. Standard export documentation accompanies every shipment: commercial invoice, packing list, certificate of origin, and HS Code 8537.10 classification. Express courier options include DHL Express, FedEx International Priority, and UPS Worldwide Express, with typical transit times of 3–5 business days to Europe and North America. For large-volume orders, sea freight consolidation via Xiamen Port is available with full container load (FCL) and less-than-container load (LCL) options.

All units carry a 12-month functional warranty covering defects in materials and workmanship from the date of shipment. Warranty claims are processed within 5 business days of receipt of the returned unit. Replacement units are dispatched from stock where available; repair or credit note is issued where replacement stock is not immediately available. Technical support — including PME configuration guidance, network setup, and fault diagnosis — is provided at no additional charge via email and WhatsApp throughout the warranty period.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
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