WhatsApp: +86 16626708626
Email: 
Phone: +86 16626708626Description
3. Key Technical Specifications
| Parameter | Value |
|---|---|
| Processor | 64 MHz 80486DX2 |
| User Memory | 1 Mbyte battery-backed (up to 512 Kbytes for logic) |
| Boolean Execution Speed | 0.4 µs per Boolean function |
| Floating Point | Yes |
| Discrete I/O (Simplex) | Up to 12K (any mix) |
| Voted Discrete I/O | 2048 inputs / 2048 outputs |
| Analog I/O (Simplex) | Up to 8K inputs / 8K outputs |
| Voted Analog Inputs | 1024 |
| Power Requirement | 3.3 A nominal from +5 V bus |
| Operating Temperature | 0–60 °C with 70 CFM forced air; 0–40 °C without |
| Serial Port | 1 × RS-422/485 compatible (programmer) |
| Slots Occupied | 1 |
| Special Requirement | Requires standalone C program for TMR operation |
4. Product Introduction
The IC697CPM790 is a high-performance single-slot CPU designed specifically for GE Fanuc Series 90-70 Triple Modular Redundancy (TMR / GMR) systems. Built around a 64 MHz 80486DX2 processor with floating-point support, it delivers 0.4 µs Boolean execution and provides 1 Mbyte of battery-backed memory (up to 512 Kbytes available for the application program).
It supports large I/O counts in both simplex and fully voted configurations and is intended for critical applications such as emergency shutdown (ESD), fire & gas, and other safety-related control systems. The module will not operate in TMR mode without the required standalone C program that handles voting and autotest routines.
5. Troubleshooting Quick Reference
| Symptom | Possible Cause | Relevance to this Part | Quick Check Method | Recommendation |
|---|---|---|---|---|
| No LEDs / CPU will not power up | Missing +5 V or backplane fault | ✅ High | Measure +5 V at the backplane; check power supply LEDs | Verify rack power and seating before replacing CPU |
| CPU OK LED off / Fault LED on | Hardware fault or missing TMR C program | ✅ High | Confirm standalone C program is loaded; check diagnostic buffer | Load correct TMR software package; replace if hardware fault persists |
| Memory loss after power cycle | Battery depleted or missing | ✅ High | Check battery age and voltage; verify IC697ACC701 installed | Replace lithium battery; note 6-month retention rating |
| Overtemperature / thermal shutdown | Insufficient forced air above 40 °C | ✅ High | Confirm 70 CFM fan is operating and filters are clean | Install or repair forced-air cooling |
| Cannot communicate via serial | Cable, baud rate, or port configuration | ⚠️ Medium | Verify RS-422/485 cable and programmer settings | Match serial parameters exactly to previous CPU |
| Voted I/O not updating | Bus controller or Genius network issue | ❌ Low | Check Genius bus controllers and network status | Problem is usually external to the CPM790 |
If basic power, battery, and software checks do not resolve the issue, replace the IC697CPM790. Always power the rack down and follow ESD procedures when handling the module.
IC697CPM790
IC697CPM790
6. Frequently Asked Questions (FAQ)
Q: What is the primary difference between the IC697CPM790 and standard 90-70 CPUs? A: The CPM790 is specifically designed for Triple Modular Redundancy (TMR/GMR) systems used in safety-critical applications. It requires a special standalone C program for voting and autotest functions and will not run correctly without it.
Q: How much memory is available for the application program? A: The module has 1 Mbyte of battery-backed memory total. Up to 512 Kbytes is available for the ladder logic / application program and data.
Q: Does it require forced-air cooling? A: Yes when ambient temperature exceeds 40 °C (104 °F). A minimum of 70 CFM of forced air is required for operation up to 60 °C. Without forced air the limit is 40 °C.
Q: Can I use this CPU in a non-redundant (simplex) system? A: Yes, it supports simplex mode with higher total I/O counts (up to 12K discrete and 8K analog). However, its main design intent and software requirements are for TMR systems.
Q: Is the Series 90-70 platform still supported? A: No. The platform is obsolete. Remaining IC697CPM790 units are new surplus or refurbished. Long-term projects should plan migration to current Emerson PACSystems platforms.
Q: Why is a new-surplus IC697CPM790 often priced lower than modern safety CPUs? A: It is an end-of-life Series 90-70 component. New-surplus stock comes from project overruns, is fully tested, and is sold at a reduced price while still carrying warranty. Condition is clearly stated as New Original / New Surplus.
Q: What battery does it use? A: The standard Series 90-70 lithium battery (IC697ACC701). Shelf life is approximately 10 years at 20 °C; memory retention is about 6 months without applied power.
