GE IC695ACC302-AB PLC Battery Module – PACSystems RX3i

GE IC695ACC302-AB — Dedicated Smart Battery Backup Module for PACSystems RX3i Control Architecture

In high-availability industrial control environments, the integrity of CPU program memory and retentive data registers during unplanned power interruptions is not a convenience feature — it is a hard operational requirement. The GE IC695ACC302-AB is the factory-designated smart battery backup module for the PACSystems RX3i platform, engineered to maintain volatile SRAM contents and the onboard real-time clock (RTC) across the full duration of a power loss event, regardless of outage length. Unlike passive battery holders found in legacy PLC families, the IC695ACC302-AB integrates an active battery management controller that continuously monitors cell voltage, charge state, and estimated remaining service life, reporting all parameters directly to the CPU over the RX3i backplane’s internal diagnostic bus.

The PACSystems RX3i platform (IC695 series) operates on a high-speed VME-derived backplane with a 32-bit parallel bus architecture capable of sustained data throughput exceeding 320 MB/s between CPU and I/O modules. Within this architecture, the IC695ACC302-AB occupies a dedicated battery slot on the CPU carrier, interfacing via a proprietary low-voltage serial link that is electrically isolated from the main backplane power rails. This isolation ensures that battery management signaling remains unaffected by transient noise events on the 24 VDC or 120/240 VAC power supply lines — a design decision that directly addresses IEC 61000-4-4 burst immunity requirements in electrically harsh plant environments.

The “-AB” hardware revision designation reflects GE’s second-generation battery management ASIC, which introduced improved coulomb-counting accuracy (±2% state-of-charge estimation versus ±8% in the -AA revision) and an extended operating temperature range. The lithium primary cell chemistry selected for this revision delivers a nominal open-circuit voltage of 3.6 V with a flat discharge curve, ensuring stable backup voltage to the CPU’s SRAM array throughout the cell’s usable life rather than exhibiting the voltage sag characteristic of alkaline chemistries that can cause marginal memory retention failures before a low-battery fault is even generated.

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Technical Parameters

Hardware Logical Analysis

The IC695ACC302-AB’s internal architecture centers on a dedicated battery management integrated circuit (BMIC) that operates independently of the main CPU clock domain. This BMIC executes a continuous coulomb-counting algorithm, integrating instantaneous discharge current over time to maintain a running state-of-charge (SoC) estimate with ±2% accuracy across the cell’s full discharge curve. The SoC value is written to a shared register accessible by the RX3i CPU via the internal diagnostic bus at each backplane scan cycle, enabling the CPU’s operating system to generate predictive low-battery warnings well before the cell voltage drops below the SRAM retention threshold of 2.0 V.

From an EMC design standpoint, the battery output path incorporates a transient voltage suppression (TVS) diode array rated at ±500 V peak pulse power, protecting the SRAM supply rail against electrostatic discharge events during module handling and against conducted transients that may couple through the CPU carrier PCB. The backup supply path is further filtered by a low-ESR ceramic capacitor bank that bridges the transition interval between main power loss detection and full battery switchover — a window measured in microseconds — preventing any voltage droop on the SRAM Vcc rail during the handoff. This design eliminates the data corruption risk that exists in simpler battery backup implementations where the switchover relay or MOSFET introduces a finite dead-time.

The real-time clock backup circuit is implemented as a separate low-power domain, drawing less than 5 µA from the lithium cell during standby. The RTC oscillator uses a temperature-compensated crystal (TCXO) with ±2 ppm frequency accuracy across the full operating temperature range, ensuring that time-stamped event logs and scheduled task triggers remain accurate to within ±1 minute per month even during extended power outages — a specification relevant to facilities that rely on PLC-generated timestamps for regulatory compliance records.

The module’s PCB layout follows IEC 61000-4-2 (ESD), IEC 61000-4-4 (EFT/Burst), and IEC 61000-4-5 (Surge) immunity design guidelines. Ground plane segmentation separates the battery management circuitry from the backplane interface logic, and all signal lines crossing the boundary are routed through common-mode chokes to suppress differential-mode noise injection into the battery management ASIC’s analog measurement inputs.

System Integration Benefits

• Bumpless Power Recovery: CPU program logic, I/O force tables, and retentive data registers are fully preserved across power loss events of any duration, enabling automatic restart without operator intervention or program reload procedures.
• Predictive Maintenance Visibility: Battery SoC and estimated remaining life are exposed as CPU system variables readable by the application program, allowing maintenance triggers to be embedded directly in the control logic rather than relying on external inspection schedules.
• Deterministic Switchover Timing: The sub-microsecond battery switchover eliminates SRAM voltage droop during power loss, preserving the deterministic scan-cycle behavior of the RX3i CPU without introducing any scan-time anomalies at the moment of power failure.
• Zero-Configuration Integration: The module is recognized automatically by the RX3i CPU upon insertion; no hardware configuration in Proficy Machine Edition is required. Battery status appears in the CPU’s I/O fault table and system status words without additional programming.
• Hot-Swap Maintenance: Battery replacement is performed with the controller energized and in RUN mode, following the documented procedure in GFK-2314. This eliminates the need for a planned production shutdown to perform routine battery maintenance.
• RTC Accuracy for Compliance Logging: The TCXO-stabilized real-time clock maintains ±2 ppm accuracy, supporting facilities where PLC-generated timestamps are used in batch records, alarm logs, or regulatory audit trails requiring traceable time references.
• Extended Temperature Tolerance: The module’s 0 °C to +60 °C operating range and -40 °C to +85 °C storage range accommodate deployment in outdoor enclosures, unheated substations, and high-ambient-temperature process areas without derating.
• Fault Isolation Architecture: The battery management circuit’s electrical isolation from the main backplane power rails ensures that a cell failure or end-of-life condition does not propagate electrical faults to the CPU or adjacent I/O modules, maintaining system availability during battery degradation.
• Revision-Controlled Compatibility: The -AB revision is backward-compatible with all IC695 CPU modules that support the smart battery interface, allowing direct replacement of -AA revision units in existing installations without firmware updates or hardware reconfiguration.
• Reduced Unplanned Downtime Cost: By eliminating program-loss recovery procedures — which typically require 2–8 hours of engineering time per incident in complex RX3i installations — the IC695ACC302-AB delivers a measurable reduction in mean time to restore (MTTR) for power-related outage events.

Quality Assurance & Global Logistics

Every IC695ACC302-AB unit supplied by siemensplc.com is sourced as genuine GE / Emerson Automation Solutions original hardware. Each module undergoes a structured pre-shipment inspection protocol that includes part number and revision verification against GE’s official documentation, physical examination of the module housing, connector integrity, PCB condition, and label authenticity. Where test equipment is available, battery cell open-circuit voltage and BMIC communication response are verified prior to packaging.

Modules are packed in anti-static ESD shielding bags, placed within rigid foam-lined cartons rated for international air freight handling per ISTA 2A transit testing standards. Export documentation — including commercial invoice, packing list, and certificate of origin — is prepared as standard for all international shipments. Material safety data sheets (MSDS/SDS) for the lithium cell are provided upon request to satisfy IATA dangerous goods documentation requirements for air freight.

Shipments originate from our warehouse in Xiamen, China, with express carrier options via DHL Express, FedEx International Priority, and UPS Worldwide Express. Typical transit times to major industrial hubs are 3–5 business days to Europe, 4–6 business days to North America, and 2–4 business days to Southeast Asia. Full shipment tracking is provided at the time of dispatch. A 12-month warranty covers manufacturing defects from the date of shipment, with replacement or credit issued following documented failure analysis.

Contact Information

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