Description

Key Technical Specifications

Parameter	Specification
Processor	80386EX, 25 MHz
User Program Memory	32 KB (RAM + Flash, non-configurable)
Typical Scan Rate	0.22 ms per 1K Boolean logic
Discrete I/O Capacity	2,048 inputs / 2,048 outputs
Analog I/O Capacity	2,048 AI words / 512 AO words
Register Memory (%R)	9,999 words
Built-in Serial Port	1× SNP/SNP-X slave (via power supply connector)
Floating-Point Math	Yes (firmware 9.0 or later)
System Expansion	Up to 8 baseplates (1 CPU + 7 expansion/remote)
Battery-Backed Clock	Yes
Power Requirement	+5 VDC, 670 mA (supplied via backplane)
Operating Temperature	0°C to 60°C (natural convection)

Product Introduction

If you have ever been called out at 2 a.m. because a CPU350 lost its program after a brownout, you know this module does not forgive sloppy maintenance. The IC693CPU350-BC sits in slot 1 of a GE Fanuc Series 90-30 rack and runs the entire show — logic execution, I/O scanning, analog calculations, and any floating-point math your process needs. It shows up everywhere from packaging lines to water treatment skids, usually because someone specified it fifteen years ago and nobody has had the budget to migrate it since.Engineers keep reaching for the CPU350 because 32 KB of memory and a 0.22 ms/1K scan rate were genuinely respectable when it shipped, and for most discrete and mid-range process tasks, they still are. The 80386EX processor handles Boolean logic without drama, and firmware 9.0+ adds floating-point support that saves you from writing your own scaling routines. One thing I will flag: the -BC suffix is a hardware revision. It drops in like any other CPU350, but always verify the installed firmware version before you swap — I have seen mismatched firmware cause timeout faults with analog modules that took half a shift to chase down.

Quality SOP & Tech Pitfalls

The Lab Report (SOP)Every unit should go through this before it reaches your rack:

Visual / counterfeit check — inspect casing, label font, connector pins, and PCB markings against known GE Fanuc reference photos.
Live test on a 90-30 test rack — power up with a known-good IC693 power supply, verify RUN/OK LEDs, and confirm the CPU enters RUN mode.
Insulation resistance and multimeter checks — verify +5 VDC backplane draw is within spec (670 mA typical).
Firmware version logging — record the firmware revision; this matters for analog module compatibility and floating-point support.
Anti-static sealing — bag in ESD-safe packaging with silica gel and a tamper-evident label.

A Fluke 115 or equivalent is fine for the voltage and current checks. Do not skip the live rack test — a module that looks clean on the bench can still fail under backplane load.The Engineer’s Warning (Pitfalls)Two mistakes will burn you with this CPU:

Firmware mismatch. If your old CPU350 is running firmware 8.x and the replacement ships with 9.x (or vice versa), you may get unexpected behavior with high-density analog modules like the IC693ALG222/223. GE published a bulletin about loss-of-module faults when multiple analog modules are active — it was resolved in later firmware revisions. Check the version before you pull the old unit.
Battery-backed memory failure. The CPU350 holds program and register data in RAM with battery backup. On older revision hardware, battery life at 60°C can drop to roughly 5½ months. I once watched a food-processing plant lose an entire weekend of recipe changes because nobody checked the BATT LED. Upload the program before you power down. Always.

Installation & Configuration Guide

Phase 1 — Pre-Installation ️

Perform a controlled safety shutdown. Lock out/tag out per your site procedure.
Wait for capacitors to discharge (typically 30 seconds minimum).
Upload and save the current program from the existing CPU350 to your engineering laptop.
Photograph the front panel LEDs, RUN/STOP/OFF switch position, and all module labels. The CPU350 has no DIP switches, but your I/O and comm modules might.
Verify you have the correct programming software: VersaPro 2.02+ or Machine Edition 2.11+.

Phase 2 — Removal

Label every cable and module slot position.
Release the DIN rail clip or rack mounting hardware carefully — the 90-30 backplane connectors are not fragile, but they are not invincible.
Pull the failed CPU straight out. Do not rock it sideways.

Phase 3 — Installation

Verify the replacement firmware revision matches your uploaded program’s expectations. If it does not, plan for a firmware update or program recompile.
Seat the new IC693CPU350-BC firmly into slot 1. You should feel the backplane connector engage fully.
Reinstall all other modules in their original slots.

Phase 4 — Power-On & Testing

Apply power. Watch the LED sequence: OK should illuminate, FAULT should be off, BATT should be off.
Confirm the CPU enters STOP mode first, then download your saved program.
Switch to RUN. Verify I/O status LEDs and run a forced I/O test on a few critical points.
Check the BATT LED. If it is lit, replace the backup battery immediately — do not defer this.

Compatible Replacement Models

Model	Compatibility Tier	Notes
IC693CPU350 (any suffix: -AA through -CF)	Drop-in Replacement	Same 32 KB, 25 MHz, 0.22 ms/1K. Firmware version must be verified. Suffix indicates hardware revision; functionally interchangeable.
IC693CPU360	️ Software Compatible	240 KB memory, same 80386EX architecture. Requires program download and may need I/O table recompile. Same rack footprint.
IC693CPU374	️ Software Compatible	133 MHz AMD SC520, 240 KB memory, dual Ethernet ports. Faster scan (0.15 ms/1K). Requires firmware flash and logic recompile. Estimate 2–4 hours engineering labor.
RX3i / VersaMax migration	Hardware Mod Required	New chassis, new I/O modules, full program conversion. Only advise this during a planned system upgrade, not an emergency swap.

Frequently Asked Questions (FAQ)

Can I hot-swap a CPU350-BC while the rack is powered?
No. The Series 90-30 CPU is not hot-swappable. You must power down the rack, replace the module, and reload the program. Hot-swapping will fault the backplane and likely corrupt your I/O table.Is the -BC suffix different from -AA or -CF?
Functionally, no. The suffix denotes a hardware revision — typically component substitutions or minor PCB changes. All CPU350 revisions share the same 32 KB memory, 25 MHz processor, and slot-1 mounting requirement. Always verify firmware version regardless of suffix.Will my existing CPU350 program run on this unit without changes?
Yes, provided the firmware revision is compatible. If your original CPU was running firmware 9.0+ and the replacement ships with an earlier version (or vice versa), you may need to update firmware or recompile. Upload your program first — that is your safety net.How long does the backup battery last?
It depends on the revision and ambient temperature. On newer revision hardware with lower-power cache RAM, expect roughly 10 months at 25°C and about 5½ months at 60°C. Replace the battery proactively every 2–3 years in warm environments. The BATT LED is your early warning.Is this module still manufactured by GE?
No. GE Fanuc discontinued the Series 90-30 line years ago. Units on the market are new surplus, unused old stock, or refurbished. Buy from a supplier that performs live rack testing and offers at least a 1-year warranty.Can I use an Ethernet module with the CPU350-BC?
Yes. The CPU350 has no built-in Ethernet port, but it supports Ethernet via the IC693CMM321 Ethernet Interface module. Note that CMM321 units must be revision -CC or later, or -AA/-BA upgraded to firmware 1.11+, for reliable communication with later CPU firmware.What happens if I lose the program and the battery dies?
You lose the RAM-stored program and register data. This is why uploading to your engineering laptop before any swap is non-negotiable. If you have no backup, you will need to reconstruct the program from documentation or HMI archives — and that is a bad day at the plant.