Mitsubishi MELSEC FX2N-32MT Modules

Technical Dossier

Product Details And Specifications

Mitsubishi Electric MELSEC FX2N Series Technical Notes

The Mitsubishi Electric MELSEC FX2N series is a compact, high-performance programmable logic controller (PLC) platform that has achieved widespread deployment across global heavy industry sectors, including petrochemical plants, nuclear auxiliary systems, oil refineries, automotive assembly lines, and water treatment facilities. Introduced in the mid-1990s as the successor to the FX2 and FX0N lines, the FX2N established itself as the dominant mid-range PLC in Asia-Pacific and European process automation markets. Its combination of high-speed instruction execution (0.08 µs/step), expandable I/O architecture (up to 256 I/O points), and broad special function module compatibility made it the reference platform for a generation of control engineers. As of 2013, Mitsubishi Electric officially announced the FX2N series as a mature/end-of-life product line, with the FX5U and iQ-F series designated as modern replacements. However, installed base volumes in legacy facilities ensure continued demand for FX2N spare parts and replacement modules through at least 2035.

The Evolution of FX2N Architecture

The FX2N architecture was built on Mitsubishi's proprietary MELSEC instruction set, offering 209 basic and applied instructions with a program capacity of 8,000 steps (expandable to 16,000 steps via memory cassette). The base unit integrates a built-in RUN/STOP switch, RS-422 programming port, and onboard power supply, eliminating the need for a separate rack chassis — a key differentiator from rack-based DCS platforms of the same era.

The FX2N series introduced the FX2N-CNV-BD communication board slot, enabling direct attachment of BD-type expansion boards (RS-232C, RS-485, USB) without consuming expansion bus slots. This modular communication architecture was carried forward into the FX3U and FX5U generations. Compatibility between FX2N special function modules and the FX3U base unit (via FX2N-CNV-IF adapter) extended the operational lifespan of FX2N peripheral investments into the 2010s. However, FX2N modules are not natively compatible with the FX5U/iQ-F platform, requiring full module replacement during migration projects.

Key architectural milestones: FX2 (1989) → FX2N (1997) → FX2NC (compact connector variant, 2001) → FX3U (2004, successor) → FX5U (2015, current generation). Engineers maintaining FX2N-based systems must account for the discontinuation of the FX2N-ROM-E1 EEPROM cassette and source alternative program backup solutions.

FX2N Full Catalog & Functionalities (SKU List)

Base CPU Units

• FX2N-16MR: 8 DC input / 8 relay output base unit, 16 I/O, 8K step program memory.
• FX2N-32MR: 16 DC input / 16 relay output base unit, 32 I/O, standard relay output configuration.
• FX2N-32MT: 16 DC input / 16 transistor (sink) output base unit, 32 I/O, 100kHz high-speed pulse output.
• FX2N-48MR: 24 DC input / 24 relay output base unit, 48 I/O, general-purpose process control.
• FX2N-48MT: 24 DC input / 24 transistor output base unit, 48 I/O, high-speed positioning applications.
• FX2N-64MR: 32 DC input / 32 relay output base unit, 64 I/O, mid-scale machine control.
• FX2N-64MT: 32 DC input / 32 transistor output base unit, 64 I/O, servo/stepper drive interface.
• FX2N-80MR: 40 DC input / 40 relay output base unit, 80 I/O, large-scale standalone control.
• FX2N-128MR: 64 DC input / 64 relay output base unit, 128 I/O, maximum onboard I/O configuration.

Digital I/O Expansion Modules

• FX2N-8EX: 8-point DC 24V input expansion module, sink/source selectable.
• FX2N-16EX: 16-point DC 24V input expansion module, standard digital input expansion.
• FX2N-8EYR: 8-point relay output expansion module, 2A per point, general load switching.
• FX2N-16EYR: 16-point relay output expansion module, mixed load applications.
• FX2N-8EYT: 8-point transistor output expansion module, 0.5A per point, high-frequency switching.

Analog I/O Special Function Modules

• FX2N-4AD: 4-channel analog input module, voltage/current selectable (±10V / 4–20mA), 12-bit resolution.
• FX2N-4DA: 4-channel analog output module, voltage/current selectable, 12-bit resolution, process setpoint output.
• FX2N-2AD: 2-channel analog input module, compact form factor for space-constrained panels.
• FX2N-1DA-R: 1-channel analog output with built-in RUN/STOP relay, dedicated single-loop control.
• FX2N-4AD-PT: 4-channel PT100 RTD temperature input module, -200°C to +600°C range.
• FX2N-4AD-TC: 4-channel thermocouple input module, K/J/T/E/R/S/B type selectable.

Communication & Network Modules

• FX2N-232-BD: RS-232C communication board, 1-channel, HMI/barcode scanner interface.
• FX2N-485-BD: RS-485 communication board, 1-channel, multi-drop network up to 50 nodes.
• FX2N-CNV-BD: Conversion board for FX0N-series BD modules, backward compatibility adapter.
• FX2N-16CCL-M: CC-Link master module, 16-station management, 10Mbps network speed.

Sourcing Hard-to-Find & Obsolete FX2N Parts

Mitsubishi Electric ceased volume production of the FX2N series in 2013 and formally ended repair services for select models by 2020. For facilities operating FX2N-based control systems — particularly in chemical processing, power generation auxiliary control, and legacy automotive body shop lines — sourcing replacement modules from the open market is the primary lifecycle extension strategy.

Quality Control for the FX2N Range

FX2N modules present specific test challenges due to their integrated backplane bus architecture and proprietary MELSEC communication protocol. DriveKNMS applies the following verification procedures to all FX2N inventory:

• Backplane Bus Integrity Test: Each base unit is connected to a reference expansion module set and verified for correct data transfer across the FX-BUS at rated clock speed. Faulty bus connectors — a common failure mode in aged FX2N units — are identified and flagged.
• I/O Point Functional Verification: All input and output points are individually cycled using automated test fixtures. Relay output modules are tested for contact resistance (<100mΩ) and minimum switching cycles.
• Analog Module Calibration Check: FX2N-4AD and FX2N-4DA modules are verified against NIST-traceable reference signals. Offset and gain register values are read and documented.
• Program Memory Retention Test: Base units with onboard RAM are subjected to a 72-hour power-off retention test to verify battery-backed memory integrity. Units with degraded backup batteries are reconditioned prior to shipment.
• Communication Port Verification: RS-422 programming ports and BD-slot communication boards are tested using GX Developer/GX Works2 connection handshake protocols.