GEIC630CPU301ASeries Three CPU / Programmer Unit — 4K Words CMOS RAM, 400 I/O Points, Built-In Ladder Programmer and Diagnostics

Product Description

What this part is

This is the CPU for a GE Fanuc Series Three programmable controller, and it is also the programmer. That combination is the whole point of the part and it is the thing most listings leave out. The IC630CPU301 contains the microprocessor that executes the ladder logic, scans the I/O and holds the user program — and on the same unit, a keypad and display for entering programs, editing them, adjusting timer and counter presets, monitoring coil and contact status, starting and stopping the program, and reading out error codes and diagnostic reports. On most PLC platforms of this era those are two purchases. On Series Three they are one.

Decoding the order code

IC630 – GE Fanuc Series Three product line (distinct from IC610 Series One, IC600 Series Six, IC693 Series 90-30)CPU – central processing unit; on this platform the CPU and programmer are the same module301 – the 4K-word CPU / programmer unitA – hardware revision letter. Revision B (IC630CPU301B) is the other commonly traded revision; revisions in this family are functionally equivalent.
Also written IC630-CPU-301-A, IC630 CPU 301 A, IC630CPU301 and, in the shorthand many maintenance departments use, GE Series 3 CPU board.

Published specifications

User memory: 4096 sixteen-bit words (4K words) of CMOS RAM; optional EPROM module available separatelyMemory retention: on-board lithium battery, accessible under a plastic cover on the underside of the moduleBattery life: up to approximately 2 years under load, 8–10 years unloaded shelf lifeMaximum I/O: 400 discrete input and output points per systemInternal relays: 368, of which 64 are retentiveTimers and counters: 128Shift registers: up to 128 wordsData registers: up to 128 wordsProgram scan rate: 28.5 msBase units per system: up to 3 — one CPU base unit plus up to two I/O base unitsBase unit sizes: 4-slot, 6-slot and 8-slot I/O module base unitsMaximum I/O modules: 8 per base unit, 24 per systemSystem supply: external 115 VAC or 230 VAC, ±15%, selected by internal jumperInput frequency: 48–63 HzMaximum load: 60 VA per base unitI/O expansion distance: up to 19 inches (approximately 50 cm) from the CPU base unit to the last I/O base unitProgramming language: ladderMounting: CPU position of the main base unit, or handheld on a 1.5 m CPU connector cable

What these specs mean in practice

Read the I/O expansion figure carefully, because it catches people out. Series Three expansion is limited to about 19 inches total from the CPU base unit to the last I/O base unit. This is not a remote I/O architecture — the three base units are intended to sit side by side in the same enclosure. If your drawing shows I/O racks in separate panels, Series Three is not the platform that was installed and you are looking at the wrong parts list.

The 1.5 m CPU connector cable is the feature that makes this unit pleasant to work with. Unplug the CPU from the base unit, hang it on the cable, and you can stand at the machine watching contact states while somebody cycles it, instead of leaning into a panel. That is genuinely useful during commissioning and fault-finding, and it is why these units are still sought after by anyone maintaining Series Three plant.

4K words is small. A 28.5 ms scan is slow by modern standards. Neither matters for what Series Three was sold to do — small to medium sequential machine control, 400 points maximum — but both are hard ceilings with no upgrade path within the platform.

The lithium battery is the risk item on any surplus unit. Under load it lasts around two years; a module that has been on a shelf for a decade has a flat cell. If the program in the CMOS RAM matters to you, treat the memory as empty until proven otherwise and have the program on paper or in an EPROM before you power anything up.

What is not included

CPU / programmer unit only. Not supplied: the 4-, 6- or 8-slot base unit; the input and output modules; the 1.5 m CPU connector cable for handheld operation; the optional EPROM memory module; a replacement lithium battery; the I/O expander cable between base units; and peripherals — the cassette tape unit, PROM writer and printer are all separate items. There is no field power supply included either; the base unit takes 115 or 230 VAC directly.

Installation and setup notes

The CPU mounts only in the CPU position of the main base unit; it cannot occupy an I/O slot and cannot go on an I/O base unit. Check the internal 115/230 VAC jumper on the base unit before applying power — a 230 V jumper on a 115 V supply simply will not run, and the reverse is expensive. Fit a fresh lithium cell before commissioning; the holder is under the plastic cover on the bottom of the module. Set timer and counter presets from the built-in keypad rather than editing the program if you are only tuning, and use the diagnostic error code readout as your first stop on a fault — it is more informative than the base unit LEDs.

Interchange guidance

Search forms include IC630CPU301A, IC630CPU301, IC630-CPU-301-A, IC630 CPU 301 A, IC630CPU301B, GEC0IC630CPU301A and GE Series 3 CPU board. Revisions A and B interchange. Series Three, Series One, Series Six and Series 90-30 are entirely separate platforms with no shared modules — an IC610, IC600 or IC693 part number will not fit a Series Three base unit and vice versa. Series Three is long discontinued with no factory replacement; surplus, reman and board-level repair are the supply channels, and CPU / programmer units are the scarcest item in the family because every system needs exactly one and there was no separate programmer to cannibalise.