Description
Hard-Numbers: Technical Specifications
- Processor: Three (3) x Intel 80486DX4 @ 96 MHz per processor
- Firmware Revision: AE (matched across all three processors in TMR set)
- Architecture: Triple Modular Redundancy (TMR) – 3-vote 2-out-of-3
- User Program Memory: 240 KB per processor (720 KB total)
- Register Memory: 240 KB per processor (720 KB total)
- Floating Point: Supported (32-bit hardware per processor)
- Discrete I/O: 2048 points max combined (%I + %Q)
- Analog Input: 128 words (%AI) per processor (up to 8K with option modules)
- Analog Output: 64 words (%AQ) per processor (up to 8K with option modules)
- Ethernet Port: 1 x RJ-45 10/100 Mbps auto-sensing (TMR-coordinated)
- Ethernet Protocols: SRTP, Modbus TCP, EGD
- Serial Ports: 2 x SNP/X (master/slave)
- Baud Rate: Up to 115.2 Kbaud
- Internal Coils (%M): 1024 bits per processor
- Timers/Counters: 340 combined per processor
- Scan Rate: 0.22 ms per 1K Boolean logic per processor (typical)
- Voting Cycle: 50-100 microseconds (processor synchronization and compare)
- Power Draw: 3.2 A @ +5 VDC (all three processors active)
- Operating Temperature: 0°C to 60°C (32°F to 140°F)
- SIL Rating: SIL 3 capable (per IEC 61508)
IC693CPU372
The Real-World Problem It Solves
Your large-scale TMR safety system is running AE firmware across all three CPU372 processors, and you need an exact-revision replacement to maintain system integrity. The AE revision provides a specific firmware baseline with proven field history for 240K memory configurations. When one processor fails, installing a different firmware revision—AF, AG, or even a different AE build—will break TMR synchronization and fault the rack. You need the exact AE revision to keep your complex safety program running without requiring a full three-processor firmware upgrade.
Where you’ll typically find it:
- Legacy Large-Scale TMR Systems: Existing Series 90-30 TMR installations with 240K memory requirements originally configured with AE firmware, often running for years without firmware changes due to re-validation requirements
- Spares Management for Complex Systems: Facilities with extensive 240K safety programs maintaining AE-revision spares to ensure compatibility with installed base
- Firmware-Stable Safety Applications: Nuclear or chemical facilities where safety system firmware changes require complete re-validation, so systems remain locked on AE revision through the asset lifecycle
Bottom line: The AE suffix identifies your firmware version—and in TMR systems with 240K memory, matching AE revisions across all three processors is mandatory for operation.
Hardware Architecture & Under-the-Hood Logic
The IC693CPU372-AE operates identically to the base IC693CPU372 in terms of hardware—three 80486DX4 processors at 96 MHz with 240KB program and register memory each, synchronized voting circuit, and backplane interface. The “-AE” designation refers only to the firmware revision loaded onto each processor, which defines execution timing, memory management, synchronization protocol, and diagnostic behavior for the 240K memory configuration. All three processors must execute identical AE firmware to ensure proper voting operation.
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AE Firmware Boot Sequence: Each of the three processors loads AE revision firmware from non-volatile memory simultaneously during power-up. AE firmware includes specific initialization routines for the 240K memory configuration, setting up memory addressing and data structures appropriate for the larger memory footprint.
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Memory Management in AE Revision: AE firmware implements the specific memory addressing scheme for 240KB program and register memories. The firmware manages memory allocation, register addressing, and data structure formats optimized for the larger memory capacity. Mismatched firmware would use different memory addressing schemes, causing voting mismatches.
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Synchronization with Large Programs: AE firmware implements the synchronization algorithm that aligns all three processors executing 240K programs. The firmware accounts for the longer program load time and execution cycle associated with larger programs, ensuring all three processors remain synchronized within the 50-100 microsecond window.
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Voting Logic for Extended Memory: AE firmware defines how the voting circuit compares outputs from three processors with 240K register memories. The firmware specifies which register ranges are voted, how memory write operations are synchronized, and how memory errors are detected and handled.
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Diagnostic Handlers for 240K Configuration: AE firmware includes diagnostic routines specific to the 240K memory configuration, testing all memory banks and detecting memory errors across the larger address space. All three processors run identical diagnostics, and results are compared by the voting circuit.
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Ethernet Stack Implementation in AE: AE firmware includes the TCP/IP stack and protocol handlers (SRTP, Modbus TCP, EGD) operating with the 240K memory configuration. Network buffers and data structures are sized appropriately for the larger memory capacity. All three processors run identical network stacks.
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Instruction Set and Timing in AE Revision: AE firmware defines the supported instruction set and execution timing for the 80486DX4 processor in the 240K configuration. Mismatched firmware would execute instructions with different timing, breaking synchronization and causing continuous voting mismatches.
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Safe-State Configuration in AE Firmware: AE firmware implements safe-state transition logic when dual-processor failures occur. The firmware defines how outputs are driven to safe state based on the 240K program configuration and safety requirements. Identical firmware ensures consistent safe-state behavior across all three processors.
IC693CPU372
Field Service Pitfalls: What Rookies Get Wrong
Mixing AE with other revisions in TMR set
You replace a failed AE processor with a newer AF revision because AE spares are unavailable. The TMR system faults immediately because AF firmware has different timing parameters and memory management for the 240K configuration. The three processors cannot synchronize.
Field Rule: Never mix firmware revisions in a TMR system. All three IC693CPU372 modules must have identical revision codes (all -AE, all -AF, etc.). Verify revision labels before installation. Use programming software to confirm firmware matches across all three processors. Maintain spares inventory with exact matching revisions. If upgrading, upgrade all three modules simultaneously during a planned outage.
Assuming CPU364 AE is compatible with CPU372 AE
You try to use a CPU364-AE spare because you’re out of CPU372-AE modules. Both have AE firmware, so you think they’re compatible. The TMR system faults because CPU364 has 80K memory and CPU372 has 240K memory—they cannot load the same program.
Field Rule: AE firmware is specific to the CPU model. CPU364-AE and CPU372-AE are not interchangeable—they have different memory sizes and different firmware implementations. The AE revision refers to firmware version within a specific model, not across models. Maintain separate spares for CPU364 and CPU372, each with their own AE revision inventory. Never assume same revision letter means same capabilities across different CPU models.
Neglecting to verify AE build number
You install a CPU372-AE spare from inventory. The revision label says AE, so you assume it’s correct. The TMR system faults because your installed base is running AE build 4.2, but the spare is AE build 4.1—a slightly older build with different timing parameters.
Field Rule: Firmware revisions have sub-build numbers (e.g., AE 4.1, AE 4.2, AE 4.3). All three processors must match on both revision letter AND build number. Use programming software to read the exact firmware version including build number. Document the build number in your maintenance log. Don’t trust revision labels alone—verify the full version. A mismatched build will break TMR synchronization.
Overlooking AE-specific diagnostic behavior
You’re troubleshooting a TMR fault and consult generic CPU372 documentation. The AE revision has specific diagnostic codes and alarm behaviors that differ from earlier or later revisions. You misinterpret the fault code and replace the wrong processor.
Field Rule: Consult AE-specific documentation and diagnostic guides. Different firmware revisions have different fault code definitions, alarm behaviors, and diagnostic procedures. The AE revision may include additional diagnostic features or modified fault reporting compared to other revisions. Use documentation specific to your exact firmware revision when troubleshooting. Don’t assume all AE builds behave identically—check the specific build documentation.
Skipping pre-replacement firmware verification
You receive a refurbished CPU372-AE from a vendor and install it without verification. The TMR system faults because the refurbished module has AE firmware loaded, but it’s a regional variant or unauthorized build that doesn’t match your system’s AE version.
Field Rule: Always verify firmware version on refurbished or third-party modules before installation. Connect the module to programming software and read the exact firmware version including build number. Verify it matches your installed base exactly. Be especially cautious with refurbished modules—vendors may load incompatible firmware versions. Document the verified firmware version before applying power.
Forgetting AE spares management for 240K systems
You maintain spares for your CPU364-AE systems but neglect your CPU372-AE inventory. A CPU372-AE fails and you have no matching AE spares. You scramble to find a compatible module while your safety system operates in degraded 2-vote mode.
Field Rule: Maintain separate spares inventories for CPU364-AE and CPU372-AE systems. The 240K memory configuration in CPU372-AE requires specific spares—CPU364-AE spares are not compatible due to memory size differences. Track firmware versions by CPU model and revision letter. Ensure spares availability for all AE-revision systems in your facility. Don’t discover spare shortages during an actual failure.
Commercial Availability & Pricing Note
Please note: The listed price is for reference only and is not binding. Final pricing and terms are subject to negotiation based on current market conditions and availability.
