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3. Key Technical Specifications
| Parameter | Value |
|---|---|
| Total Memory | 192K |
| User MegaBasic Memory | 47K |
| Supported Protocols | Modbus RTU, GE Fanuc CCM |
| Programming Languages | MegaBasic, C |
| Serial Ports | 2 (accessed via single 25-pin D-shell connector) |
| Port Connector | 25-pin D-shell (Ports 1 & 2 combined) |
| Backplane Current | 425 mA @ +5 VDC |
| Battery Backup | Lithium battery (IC693ACC301 replacement) |
| LED Indicators | OK, US1, US2 (plus BD OK / P1 OK / P2 OK on some views) |
| Restart | Front-panel Restart pushbutton |
| Mounting Location | CPU baseplate only (any slot except CPU slot 1) |
| Incompatible With | Embedded CPUs (311/313/323), expansion or remote racks |
| Compatible Cables | IC693CBL304/305 (Wye), IC690CBL701/702/705 |
4. Product Introduction
The GE Fanuc IC693PCM301 is a Programmable Coprocessor Module for Series 90-30 modular CPUs. It adds independent processing power and dual serial communications to the PLC, supporting Modbus RTU and GE Fanuc CCM protocols. The module carries 192K of total memory with 47K available for MegaBasic programs and can also run C applications.
Both serial ports are brought out through a single 25-pin D-shell connector on the front panel. Typical uses include interfacing with programming terminals, CRTs, barcode readers, scales, printers, ASCII devices, and RTU master equipment. The module must be installed in the main CPU baseplate (any slot except the CPU itself) and will not operate in expansion or remote racks or with embedded CPU models 311/313/323.
IC693PCM301
IC693PCM301
5. Troubleshooting Quick Reference
| Symptom | Possible Cause | Relevance to this Part | Quick Check Method | Recommendation |
|---|---|---|---|---|
| OK LED off | Module not powered or fatal fault | ✅ High | Measure +5 VDC on backplane; reseat module | Verify power supply and slot contact; press Restart |
| US1 / US2 LEDs never flash | No serial activity or cable problem | ✅ High | Check cable continuity and pinout; monitor port with terminal program | Confirm correct Wye or dual-port cable and baud settings |
| Program lost after power cycle | Dead backup battery | ✅ High | Measure battery voltage; replace if low | Install fresh IC693ACC301 battery and restore program |
| Module will not initialize | Wrong baseplate or incompatible CPU | ✅ High | Confirm installation is in main CPU rack only, not expansion/remote | Move to CPU baseplate; verify CPU is modular type (not 311/313/323) |
| Communication errors on both ports | Shared connector or ground loop | ✅ Medium | Test each port independently with known-good cable | Use proper Wye cable; check shield grounding |
| Restart button has no effect | Module hung or hardware failure | ✅ Medium | Power-cycle the rack and retry | If still unresponsive, replace module |
If the module continues to fail after these checks, photograph the faceplate LEDs, note the exact cable used, and capture any diagnostic messages before contacting technical support.
6. Frequently Asked Questions (FAQ)
Q: Is the IC693PCM301 still manufactured? A: No. The Series 90-30 platform is mature. Available units are New Surplus or tested refurbished stock. Keep spares if the system relies on the PCM for critical communications or custom code.
Q: Where can I install this module? A: Only in the main CPU baseplate, any slot except the CPU slot itself (slot 1). It will not operate in expansion or remote racks and is incompatible with embedded CPUs (311, 313, 323).
Q: How much user memory is available? A: Total memory is 192K; approximately 47K is available for MegaBasic programs. The higher-memory IC693PCM311 offers 640K total / 190K MegaBasic if more space is required.
Q: What protocols and languages does it support? A: Modbus RTU and GE Fanuc CCM for communications. Application code can be written in MegaBasic or C. A free RTU Master example program was historically available from GE Fanuc.
Q: How are the two serial ports accessed? A: Both ports share a single 25-pin D-shell connector on the front of the module. A Wye cable (IC693CBL304/305 or equivalent) is required to break the connector out into two separate ports.
Q: Does the battery need to be connected? A: Yes, if you need to retain the RAM-based program across power cycles. The lithium battery (IC693ACC301) mounts on the inside of the faceplate. Disconnect it for long-term storage to avoid deep discharge.
Q: Can this module be hot-swapped? A: No. Power down the rack before inserting or removing the module. Hot-swapping risks damage to the backplane and the PCM.
Q: Why is New Surplus priced lower than original list? A: These are unused original modules from OEM or distributor surplus inventory. Each unit is visually inspected, powered on a genuine Series 90-30 rack, and verified for basic LED and port response before shipment. Test documentation is available on request.
