OMRON E5AK Series Process Controllers — E5AK-AA2

Technical Dossier

Product Details And Specifications

OMRON E5AK Series: Comprehensive Module Range and Technical Overview

The OMRON E5AK series is a DIN 96×96mm advanced digital process controller widely deployed across global heavy industry sectors including petrochemical refineries, nuclear power auxiliary systems, pharmaceutical batch processing, and steel mill temperature management. Its dual-loop PID control architecture, combined with universal input compatibility (thermocouple, RTD, analog voltage/current), has made it a standard-specification instrument in facilities requiring long-term process stability. The E5AK platform supports RS-485 serial communication, enabling integration into SCADA and DCS environments without gateway hardware. Its installed base spans Asia-Pacific, Europe, and the Middle East, with documented deployments in facilities operated by BASF, Sinopec, and TEPCO affiliates. As of 2026, the E5AK series has entered its mature-to-end-of-life phase; OMRON has transitioned new projects to the E5CC and E5DC platforms, but the E5AK remains the dominant controller in legacy systems requiring 10–20 year maintenance horizons.

The Evolution of E5AK Architecture

The E5AK was introduced in the mid-1990s as OMRON's response to demand for a compact, high-accuracy process controller capable of replacing analog panel instruments in retrofit projects. Its predecessor, the E5A series, offered basic on/off and PID control but lacked digital communication capability. The E5AK introduced RS-485 (CompoWay/F protocol) as a standard feature, enabling multi-drop network configurations of up to 32 units on a single bus segment.

The architecture uses a modular input/output design: the base unit accepts a universal analog input, while output configuration is determined by the suffix code (relay, voltage pulse, current, or linear). This suffix-based variant system — e.g., AA2 for current output, PR2 for relay output — allows facilities to standardize on a single controller platform while adapting output type to actuator requirements (control valves, SCR drives, heaters).

Compatibility considerations for legacy integration: E5AK units use a 96×96mm panel cutout (DIN standard), compatible with E5C2, E5CS, and E5S cutouts with adapter rings. The CompoWay/F RS-485 protocol is directly compatible with OMRON PLCs (CJ, CS, CX series) and third-party SCADA systems via Modbus RTU converters. Units manufactured before 2005 use a 5-pin RS-485 connector; post-2005 units use a 3-pin terminal block — a critical distinction for direct replacement in existing wiring harnesses.

The E5AK was succeeded by the E5AN (96×96mm, enhanced display) and later the E5CC (48×48mm compact) and E5DC (DIN rail mount) for new installations. Cross-compatibility of parameters via OMRON's CX-Thermo software allows configuration migration from E5AK to E5AN without manual re-entry of PID parameters.

E5AK Full Catalog & Functionalities (SKU List)

The following SKUs represent the verified production range of the OMRON E5AK series, classified by output type and auxiliary function configuration. All models share the 96×96mm DIN form factor, universal analog input, and RS-485 CompoWay/F communication.

Current Output Models (4–20 mA)

• E5AK-AA2: Dual-loop PID controller, 4–20 mA current output, universal input (TC/RTD/analog), RS-485, 100–240 VAC supply.
• E5AK-AA2-500: E5AK-AA2 with extended 500 ms sampling cycle option for high-thermal-mass processes.
• E5AK-AA2-FLK: E5AK-AA2 with factory-configured failsafe output latch on sensor break detection.

Relay Output Models

• E5AK-PR2: Single-loop PID, SPDT relay output (250 VAC / 3A), universal input, RS-485.
• E5AK-PR2-500: E5AK-PR2 with 500 ms sampling cycle, suited for furnace temperature control.
• E5AK-PRR2: Dual relay output (main control + alarm), universal input, RS-485.

Voltage Pulse Output Models (for SSR Drive)

• E5AK-TAA2: Voltage pulse output (12 VDC, 40 mA) for solid-state relay drive, universal input, RS-485.
• E5AK-TAA2-500: E5AK-TAA2 with 500 ms sampling cycle.
• E5AK-TRR2: Dual voltage pulse output, independent PID loops, RS-485.

Heating/Cooling Control Models

• E5AK-AA2-HCN: Heating/cooling PID, current output for heating + relay for cooling, universal input.
• E5AK-PRR2-HCN: Heating/cooling PID, dual relay output configuration.

Linear Voltage Output Models

• E5AK-VA2: 0–10 VDC linear output, universal input, RS-485, for proportional valve control.
• E5AK-VA2-500: E5AK-VA2 with 500 ms sampling cycle.

Special Function / Communication Models

• E5AK-AA2-COM: Enhanced RS-485 communication variant with extended register map for SCADA integration.
• E5AK-PRR2-COM: Dual relay output with enhanced communication register map.
• E5AK-AA2-DRT: DeviceNet-compatible variant for integration into OMRON CJ/CS DeviceNet networks.
• E5AK-AA2-MLT: Multi-loop variant supporting cascade PID configuration via internal setpoint transfer.

Sourcing Hard-to-Find & Obsolete E5AK Parts

The E5AK series reached end-of-production status in most regional markets between 2018 and 2022. OMRON's official spare parts program covers select high-volume variants through authorized distributors, but low-volume suffix configurations (e.g., -FLK, -DRT, -MLT) are no longer stocked in standard distribution channels.

DriveKNMS maintains a dedicated inventory of E5AK series units sourced from decommissioned plant equipment, authorized surplus channels, and long-term storage facilities. All units are catalogued by suffix code, firmware revision, and manufacture date. For facilities operating E5AK controllers in critical process loops — where a 48-hour replacement window is a contractual requirement — DriveKNMS provides pre-tested exchange units with documented test records.

For end-users evaluating migration to E5AN or E5CC platforms, DriveKNMS provides parallel sourcing: E5AK units for immediate replacement needs alongside E5AN units for phased upgrade projects, eliminating the need to manage two separate supplier relationships.

Typical lead time for in-stock E5AK variants: 1–3 business days (ex-warehouse). For rare suffix configurations: 5–15 business days subject to sourcing availability.

Quality Control for the E5AK Range

Each E5AK unit processed by DriveKNMS undergoes a structured test protocol addressing the specific failure modes documented in this series:

• Input accuracy verification: Thermocouple (K, J, T, E, L, U, N, R, S, B types) and RTD (Pt100, JPt100) inputs are verified against NIST-traceable reference standards at 0%, 50%, and 100% of span. Accuracy must meet ±0.3% FS or better.
• Output calibration: Current output (4–20 mA) is verified at 4 mA, 12 mA, and 20 mA against a calibrated loop calibrator. Relay output contact resistance is measured (<100 mΩ acceptable).
• RS-485 communication test: Unit is connected to a CompoWay/F test master. All register read/write operations are verified. Baud rate stability at 9600, 19200, and 38400 bps is confirmed.
• Display and keypad function test: All front-panel keys are actuated. Display segment integrity is verified under full-brightness condition.
• Power supply range test: Unit is powered at 85 VAC (low-line) and 264 VAC (high-line) to verify operation across the full rated supply range.
• Thermal soak: Unit operates continuously for 2 hours at ambient 40°C to screen for intermittent component failures common in aged electrolytic capacitors.

Test records are retained for 24 months and are available to customers upon request.

For E5AK sourcing inquiries, replacement unit requests, or technical specification questions:

• Email: sale@driveknms.com
• WhatsApp: +86 18359293191
• Web: driveknms.com

© 2026 DriveKNMS. All trademarks belong to their respective owners. Specifications are for reference only and subject to change without notice. Verify all parameters against official documentation before installation.