GE IC693APU300 Retrofit-Compatible APU for Legacy Systems

GE IC693APU300 Retrofit-Compatible Arithmetic Processing Unit for Legacy Series 90-30 Systems

The GE IC693APU300 is a high-performance Arithmetic Processing Unit (APU) designed for the GE Series 90-30 Programmable Logic Controller platform. As manufacturing facilities continue to operate aging automation infrastructure, the IC693APU300 has become a critical spare part and retrofit component for engineers tasked with extending the operational life of Series 90-30 control systems. Whether you are replacing a failed unit, upgrading processing capacity in an existing rack, or migrating from an older co-processor module, the IC693APU300 delivers the computational throughput needed to sustain complex math-intensive ladder logic, floating-point calculations, and real-time process control without requiring a full system replacement.

At NINERMAS, every IC693APU300 unit is pre-shipment tested under simulated rack conditions, verified for backplane communication integrity, and supplied with a 12-month warranty covering both parts and workmanship. Our inventory program is designed to support long-lifecycle industrial automation environments where procurement lead times and supply continuity are mission-critical.

Upgrade Compatibility Table

Retrofit Planning for Existing Automation Systems

Integrating the IC693APU300 into an existing Series 90-30 control system requires a structured approach to avoid unplanned downtime and configuration errors. The first step is a physical audit of the target rack — typically an IC693CHS391 (5-slot) or IC693CHS392 (10-slot) chassis — to confirm that an available slot exists and that the installed IC693PWR321 or IC693PWR330 power supply has sufficient current headroom to support the additional module load. APU modules draw from the backplane’s 5V bus, and in heavily populated racks with multiple IC693MDL655 discrete output modules or IC693ALG392 analog input modules, the power budget must be recalculated before installation.

Once the physical slot is confirmed, the engineering team should review the existing ladder logic program in Proficy Machine Edition to identify all APU instruction blocks (TRIG, LOG, SQRT, PID math extensions) that will be routed to the IC693APU300. In systems previously running without an APU, these blocks may have been handled by the main CPU — either an IC693CPU364 or IC693CPU374 — at reduced throughput. Adding the IC693APU300 offloads these calculations, improving scan time performance and freeing CPU resources for I/O handling and communications tasks.

For facilities also managing communications upgrades, the IC693APU300 coexists cleanly with the IC693CMM302 CCM module for legacy serial networks and the IC693CMM311 Ethernet Interface for modern TCP/IP connectivity. If the retrofit scope includes migrating from a legacy Genius Bus network — managed through an IC693BEM331 Bus Controller — to a PROFIBUS or Ethernet-based architecture, the APU’s presence ensures that math-intensive control loops continue to execute at full speed during the transition period, even as communications modules are swapped and reconfigured.

HMI integration is another key consideration. Many Series 90-30 installations use CIMPLICITY or iFIX SCADA systems connected via the IC693CMM311 or a dedicated IC693CPU374 Ethernet port. After installing the IC693APU300, verify that any HMI data tags referencing APU-computed values (such as flow totals, PID outputs, or calculated setpoints) are correctly mapped and that the SCADA polling rate does not create backplane contention. Signal isolators on analog input channels — particularly on IC693ALG392 or IC693ALG442 modules — should also be inspected to ensure that the analog signal chain remains stable during the retrofit commissioning phase.

Terminal wiring and I/O module addressing do not change with an APU installation, as the IC693APU300 occupies a dedicated processing slot and does not consume I/O addresses. However, if the retrofit also involves replacing failed IC693MDL240 AC input modules or adding new IC693MDL740 DC output modules to expand I/O capacity, the I/O address map must be updated in the program and verified against the field wiring schedule before the system is returned to service.

Downtime Control During System Migration

Minimizing production downtime during a Series 90-30 retrofit is achievable with disciplined pre-commissioning preparation. Before the maintenance window opens, the engineering team should perform a full program backup from the existing CPU using Proficy Machine Edition, saving both the ladder logic and the hardware configuration file. This backup serves as the rollback baseline if any issue arises during the APU installation.

The IC693APU300 is a hot-rack-insertable module in powered-down slot conditions — meaning the rack should be de-energized before module insertion to protect the backplane connectors. Once installed, the rack can be powered up and the CPU will automatically recognize the APU during its initialization scan. No firmware download to the APU is required; the module is configured entirely through the ladder program’s APU instruction blocks.

For systems where continuous control is required, a parallel rack strategy can be employed: a spare IC693CHS392 chassis pre-loaded with the IC693APU300, the target CPU (IC693CPU364), and the necessary I/O modules can be configured and tested offline, then swapped into the control cabinet during a planned outage window. This approach reduces live commissioning time to the duration of the physical swap and field wiring reconnection, typically achievable within a two- to four-hour maintenance window.

Post-installation, the commissioning checklist should include: APU block execution verification in the ladder scan, analog loop stability confirmation, HMI tag validation, communications link re-establishment (CCM or Ethernet), and a full I/O force test on critical output channels. All test results should be documented and retained as part of the site’s change management record.

Retrofit Support FAQ

Q1: Is the IC693APU300 a direct replacement for a failed unit in an existing Series 90-30 rack?
Yes. The IC693APU300 is a like-for-like replacement. No program changes are required for a direct swap. After installation, cycle power to the rack and verify that the CPU recognizes the APU during the hardware configuration scan in Proficy Machine Edition.

Q2: What pre-shipment testing does NINERMAS perform on the IC693APU300?
Each unit undergoes functional verification in a live Series 90-30 rack, including backplane communication checks, APU instruction execution tests, and power consumption measurement. A test report is available upon request. All units are covered by a 12-month warranty from the date of shipment.

Q3: Can the IC693APU300 be used in a rack that also contains communication modules such as the IC693CMM311?
Yes. The IC693APU300 operates independently on the backplane and does not conflict with communication modules. Ensure the power supply (IC693PWR321 or IC693PWR330) has sufficient capacity for the combined module load before finalizing the rack configuration.

Q4: What is the lead time and inventory availability for the IC693APU300?
NINERMAS maintains stock of the IC693APU300 to support urgent retrofit and breakdown replacement requirements. Standard orders ship within 3–5 business days. For volume procurement or long-term supply agreements supporting multi-site retrofit programs, contact our sales team to discuss dedicated inventory reservation and fixed lead-time commitments.