Description
Key Technical Specifications
- Processor: Motorola 68000 Family (68K)
- Flash Memory: 2 MB
- NVRAM: 512 KB (Battery-backed)
- SRAM: 1.5 MB
- Bus: VMEbus
- Serial Ports: 8x RS-232 (via D20M SIO module)
- Boot ROM: Factory installed basic software
- Operating Temp: 0°C to +60°C
- Mounting: VME Rack (Single Slot)
- Application: WESDAC D200 Control System
Product Introduction
The GE WESDAC D20ME is the brain of the WESDAC D200 VME control system. Built around the Motorola 68K architecture, this CPU board manages all logic execution, I/O scanning, and communication for the entire rack. It’s not a modern PLC; it’s a dedicated industrial computer from an era when “embedded” meant a 68000 and a bunch of discrete RAM chips.
You’re looking at this board because your D200 system is down and the OEM stopped supporting it years ago. The GE WESDAC D20ME holds your application code in 2MB of Flash and keeps critical data alive with 512K of NVRAM. With 1.5MB of SRAM for runtime, it handles the scan cycles for dozens of I/O modules. Bottom line: if this CPU dies, your entire WESDAC system is a paperweight. Verify your memory config before ordering—some variants have different Flash/RAM splits.
Troubleshooting Quick Reference
| Fault | Cause | Relevancy | Quick Check | Fix |
|---|---|---|---|---|
| No Boot / Dead LEDs | NVRAM Battery Dead | 90% | Measure battery voltage on CPU. Check for “Battery Low” in diagnostics. | Replace CR2032/BR2325. Reload config if corrupted. |
| System Hangs | Flash Corruption | 80% | Check diagnostic LEDs. Try power cycle. | Reload application via WESMAINT. If no fix, replace GE WESDAC D20ME. |
| Comm Loss | Serial Port Failure | 70% | Test WESMAINT port. Check cable termination. | Swap to backup port. If all fail, replace CPU. |
| Erratic Logic | SRAM Failure | 60% | Check for memory errors in diagnostics. | Run memory test. Replace GE WESDAC D20ME if errors persist. |
| No Power | Backplane Fuse | 50% | Measure +5V at VME connector. | Check backplane fuse. Replace CPU if input is good but dead. |
Application Scenarios & Pain Points
- Water/Wastewater Treatment: 25-year-old WESDAC systems still running pump stations. Pain point: Original CPUs failing from capacitor plague. The GE WESDAC D20ME is the only drop-in fix without reprogramming the entire plant.
- Mining Conveyors: Remote sites with legacy GE controls. Pain point: No local support. The GE WESDAC D20ME ships overnight, avoiding weeks of downtime waiting for a specialist.
- Chemical Batch Processing: Critical recipe control. Pain point: NVRAM loss wipes calibration data. The ’s battery-backed memory keeps recipes alive through power cycles.
