GE Series 90-70 IC697CPU788 Central Processing Unit

Technical Dossier

Product Details And Specifications

GE Series 90-70 Series Technical Notes

The GE Series 90-70 (IC697 prefix) is GE Automation & Controls' rack-based programmable logic controller platform, deployed across heavy industrial sectors including petrochemical refineries, nuclear power generation, pulp and paper mills, and offshore oil & gas facilities. First introduced in the late 1980s, the Series 90-70 established itself as a high-density, high-throughput PLC architecture capable of handling complex ladder logic, function block diagrams, and structured text programs under IEC 61131-3. Its VME-based backplane architecture supports up to 21 slots per rack, enabling large-scale I/O configurations that remain in active service at thousands of global installations. The IC697CPU788 is a 32-bit CPU module within this platform, executing user programs at high speed with expanded memory capacity relative to earlier CPU variants in the same family.

The Evolution of Series 90-70 Architecture

The Series 90-70 architecture progressed through several CPU generations, each addressing processing speed, memory capacity, and communication capability constraints of its era. The earliest CPUs — IC697CPU731 and IC697CPU771 — operated with limited user memory (32KB–128KB) and single-task execution models. The mid-generation IC697CPU772 and IC697CPU781 introduced expanded RAM and faster scan cycle performance. The IC697CPU788 and IC697CPU789 represent the high-end tier of the Series 90-70 CPU range, offering 512KB to 1MB of user memory, floating-point math coprocessor support, and compatibility with the full IC697 I/O module library.

The platform's VME backplane (IC697CHS750, IC697CHS782, IC697CHS790) remained consistent across generations, ensuring backward compatibility for I/O modules. However, CPU firmware versions must be matched to the Logicmaster 90-70 or Proficy Machine Edition programming software version in use. Mixing incompatible firmware and software versions is a documented source of configuration faults in legacy installations. The Series 90-70 has been in the mature/end-of-life phase since the mid-2010s, with GE (now part of Emerson) having transitioned customers toward the PACSystems RX7i platform, which uses the same VME mechanical form factor but a different CPU and backplane architecture.

Series 90-70 Full Catalog & Functionalities (SKU List)

CPU Modules

• IC697CPU731: 32KB user memory CPU, single-rack standalone controller for small applications.
• IC697CPU771: 128KB user memory CPU, supports floating-point math, early-generation high-performance option.
• IC697CPU772: 256KB user memory CPU, enhanced scan performance over IC697CPU771.
• IC697CPU781: 512KB user memory CPU, supports C programming blocks and expanded I/O.
• IC697CPU788: 512KB user memory CPU with floating-point coprocessor, high-speed execution, full IC697 I/O compatibility.
• IC697CPU789: 1MB user memory CPU, top-tier Series 90-70 processor, supports redundancy configurations.

Discrete Input Modules

• IC697MDL340: 32-point 24VDC discrete input module, isolated, high-density rack mount.
• IC697MDL341: 32-point 120VAC discrete input module, standard industrial voltage range.
• IC697MDL653: 32-point 24VDC positive logic discrete input, grouped commons.

Discrete Output Modules

• IC697MDL940: 32-point 24VDC discrete output module, 0.5A per point, sourcing type.
• IC697MDL753: 32-point relay output module, Form A contacts, 2A per point.

Analog I/O Modules

• IC697ALG320: 16-channel analog input module, 4–20mA / 0–10V configurable per channel.
• IC697ALG321: 8-channel analog input, high-resolution 16-bit ADC, thermocouple/RTD compatible.
• IC697ALG440: 8-channel analog output module, 12-bit DAC, 4–20mA output range.

Communication & Network Modules

• IC697CMM711: Serial communications module, RS-232/RS-485, supports SNP and SNPX protocols.
• IC697CMM742: Ethernet TCP/IP communications module, 10BaseT, SRTP and Modbus TCP support.
• IC697BEM711: Genius Bus Controller, interfaces Series 90-70 CPU to Genius I/O bus network.

Power Supply Modules

• IC697PWR710: 120/240VAC input power supply, 30W output, standard rack power for IC697 chassis.
• IC697PWR711: 24VDC input power supply, 30W, for DC-powered panel installations.

Quality Control for the Series 90-70 Range

Series 90-70 modules present specific test challenges due to their VME backplane bus architecture and the age-related failure modes common to CMOS logic ICs and electrolytic capacitors manufactured in the 1990s. DriveKNMS applies the following test protocol to all IC697-series modules prior to dispatch:

• Visual inspection for PCB corrosion, damaged edge connectors, and capacitor bulge.
• Powered functional test using a reference IC697 rack with known-good CPU and power supply.
• For CPU modules (including IC697CPU788): firmware version read-back, user memory write/read cycle test, and watchdog timer verification.
• For analog modules: channel-by-channel calibration verification against NIST-traceable reference instruments.
• For communication modules: loopback test on all serial ports; Ethernet modules tested for SRTP session establishment.
• Burn-in period: minimum 24 hours powered operation before final inspection and packaging.