GE-FanucIC693CPU331KSeries 90-30 Single-Slot CPU Module, 80188 10 MHz, 16K Program Memory, 512 Discrete In / 512 Discrete Out

Product Description

What this part is

This is a Series 90-30 single-slot CPU module — the processor that runs the ladder program in a GE Fanuc Series 90-30 programmable controller. It drops into the CPU slot of a 5-slot or 10-slot baseplate, scans the I/O modules across the backplane, executes user logic and holds the register and reference tables. Series 90-30 was one of the most widely installed small PLC platforms in North American industry, and the CPU is the one module in the rack you cannot substitute with something from another family.

Decoding the order code

IC693 – GE Fanuc Series 90-30 product lineCPU – central processing unit module (as distinct from MDL discrete I/O, ALG analog, CMM communications, APU motion)331 – the specific CPU model: 80188 processor, 16K user program memory, single-slot form factorK – hardware revision letter. Revision letters in this family track internal component changes and are functionally interchangeable; match the 331 first and check the letter against your maintenance parts list only if your site controls to revision.
Also written IC693-CPU-331-K, IC693 CPU 331 K and IC693CPU331.

Correcting the source data

Earlier copy on this listing gave the brand as Fanuc. The Series 90-30 line is GE Fanuc — the joint venture between GE Fanuc Automation and Fanuc Ltd, later GE Intelligent Platforms and now Emerson. Fanuc-branded CNC boards carry A-prefix numbers such as A16B and A20B; anything with an IC693, IC600, IC610 or IC630 prefix is the GE side of the house. It matters when you search, because the two catalogues share almost no part numbers.

Note also that this is a single-slot CPU module. Some resale listings describe the CPU331 as an integrated CPU-plus-10-slot-baseplate unit. It is not; that description belongs to the embedded CPU311/CPU313/CPU323 style boards. The CPU331 is a module and it needs a baseplate.

Published specifications

CPU type: single-slot CPU moduleProcessor: 80188, 16-bitProcessor speed: 10 MHzUser program memory: 16K bytes maximumTypical scan rate: 0.4 ms per 1K of Boolean logicDiscrete inputs %I: 512Discrete outputs %Q: 512Register memory %R: 2048 wordsAnalog inputs %AI: 128 wordsAnalog outputs %AQ: 64 wordsDiscrete global memory %G: 1280 bitsInternal coils %M: 1024 bitsTemporary coils %T: 256 bitsSystem status %S, %SA, %SB, %SC: 32 bits each, 128 bits totalBaseplates per system: 5 maximum — one CPU baseplate plus up to four expansion and/or remoteBackplane load: 350 mA from the +5 VDC supplyOperating temperature: 0 to 60 °C ambientMaths: integer operations only, no floating-point hardware

What these specs mean in practice

16K bytes of program space is the defining limit of this CPU. It is fixed — there is no memory expansion option for a CPU331. If your application outgrows it you move up to a CPU340/341/350 class processor, not add memory to this one. For sequential machine control, conveyor and packaging logic, and most retrofit applications where the CPU331 was originally specified, 16K is ample; a scan of 0.4 ms per 1K of Boolean means even a full program scans in single-digit milliseconds.

Integer-only arithmetic is the other thing to check before buying. If the program you are supporting uses floating-point maths function blocks, this CPU cannot execute them. Recipe handling, PID with scaled real values and any temperature or flow computation in engineering units are the usual places that bites. Fixed-point scaling in integer registers is the standard workaround and is how most CPU331 programs were originally written.

512 discrete in and 512 discrete out is a large I/O count for a five-baseplate system, so in practice the reference table is rarely the constraint — slots and program memory are.

What is not included

This is the CPU module only. Not supplied: the 5-slot or 10-slot baseplate (IC693CHS39x/CHS40x family), the rack power supply (IC693PWR321 or PWR330), the memory backup battery (IC693ACC301), the SNP/RS-485 programming cable and any RS-232 converter, expansion or remote baseplate cables, and any option module — Ethernet, Genius, Profibus or serial communications cards are all separate catalogue items. If you are building a rack from scratch, budget for baseplate, power supply and battery alongside this module.

Installation and setup notes

The CPU331 installs in the leftmost CPU slot of the baseplate, adjacent to the power supply; it cannot be placed in a general I/O slot. Fit a fresh lithium backup battery before you commission — a surplus CPU has almost certainly been sitting long enough that the original cell is flat, and losing the program on the first power cycle is an avoidable morning. The serial port is SNP protocol over RS-485 for programming with Logicmaster 90-30, VersaPro or Proficy Machine Edition; a Hand Held Programmer will also talk to it. Always power the rack down before inserting or removing the CPU.

Interchange guidance

Search forms include IC693CPU331K, IC693CPU331, IC693-CPU-331-K and IC693 CPU 331 K. The CPU331 sits between the entry-level embedded CPUs and the CPU340-and-up processors; those are related models with different memory and features, not drop-in equivalents — program capacity and instruction support differ, so a swap is a re-engineering exercise rather than a like-for-like replacement. Within the CPU331 designation, revision letters are the interchangeable dimension. Series 90-30 is discontinued and legacy-supported; surplus, reman and board-level repair are the supply channels.