Mitsubishi MELSEC FX2N Modules: FX2N-4AD

Technical Dossier

Product Details And Specifications

Mitsubishi MELSEC FX2N Series: Comprehensive Module Range and Technical Overview

The Mitsubishi 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 continuous process manufacturing. Introduced in the mid-1990s as the successor to the FX2 and FX0N families, the FX2N established itself as the dominant small-to-mid-range PLC in Asia-Pacific and European markets. Its modular expansion architecture, deterministic scan cycle, and broad I/O compatibility made it the reference platform for machine builders and system integrators operating under IEC 61131-3 constraints. Installed base estimates exceed several million units globally, with a significant proportion still in active service within legacy SCADA and DCS hybrid architectures.

The Evolution of FX2N Architecture

The FX2N architecture is built around a fixed CPU base unit with a right-side expansion bus that accepts up to eight special function modules and 16 extension units, supporting a maximum of 256 discrete I/O points. The internal bus operates at 5 VDC with a 24 VDC field power rail, a design inherited from the FX2 but significantly re-engineered for higher-speed FROM/TO instruction throughput. Early FX2N base units (circa 1997–2001) used mask ROM firmware and required physical chip replacement for version upgrades. Post-2002 units adopted flash-based firmware, enabling field updates via RS-422 programming port.

Compatibility across the FX2N generation is largely maintained at the hardware level: expansion modules from the FX2N, FX2NC, and FX3U families share the same physical bus connector, though software addressing differs between generations. The FX3U, introduced in 2004, is the direct architectural successor and maintains backward compatibility with most FX2N special function modules via adapter units (FX2N-CNV-BC). The FX5U (2016) represents a full platform break, using a high-speed USB/Ethernet programming interface and incompatible expansion bus — FX2N modules are not directly compatible without gateway hardware.

Mitsubishi Electric officially announced end-of-production for the FX2N CPU base units in 2013, with repair service support extended through 2023. As of 2026, the FX2N series is in full lifecycle termination phase. Spare parts, including the FX2N-4AD, are sourced exclusively through authorized distributors and specialist industrial spare parts suppliers.

FX2N Full Catalog & Functionalities (SKU List)

Analog Input Modules

• FX2N-4AD: 4-channel analog input, 12-bit resolution, voltage/current selectable per channel, FROM/TO instruction interface.
• FX2N-8AD: 8-channel analog input, 12-bit resolution, supports thermocouple and voltage/current inputs simultaneously.
• FX2N-4AD-PT: 4-channel Pt100 RTD temperature input module, -200°C to +600°C range, 0.1°C resolution.
• FX2N-4AD-TC: 4-channel thermocouple input module, supports K, J, T, E, R, S, B type thermocouples.

Analog Output Modules

• FX2N-4DA: 4-channel analog output, 12-bit resolution, voltage (0–10 V / ±10 V) or current (4–20 mA) selectable.
• FX2N-2DA: 2-channel analog output, 12-bit, compact form factor for space-constrained panels.

Digital I/O Extension Units

• FX2N-16EX: 16-point DC input extension unit, 24 VDC sink/source compatible.
• FX2N-16EYR: 16-point relay output extension unit, 2A per point, 250 VAC/30 VDC rated.
• FX2N-16EYT: 16-point transistor output extension unit, NPN open-collector, 0.5A per point.
• FX2N-32ER: 32-point combined I/O extension (16 in / 16 relay out), integrated power supply.
• FX2N-48ER: 48-point combined I/O extension (24 in / 24 relay out).

Communication & Network Modules

• FX2N-232-BD: RS-232C communication board, mounts directly on CPU base unit, supports HMI and barcode scanner interfacing.
• FX2N-485-BD: RS-485 communication board, supports Modbus RTU and Mitsubishi N:N network protocol.
• FX2N-232IF: RS-232C interface module (external expansion type), full-duplex, 19200 bps max.
• FX2N-16CCL-M: CC-Link master module, supports up to 64 remote I/O stations, 10 Mbps network speed.
• FX2N-32CCL: CC-Link remote device station module, 32-point I/O mapping to CC-Link network.

CPU Base Units

• FX2N-16MR-001: 16-point CPU base unit, 8 DC inputs / 8 relay outputs, 8K step program memory.
• FX2N-32MR-001: 32-point CPU base unit, 16 DC inputs / 16 relay outputs.
• FX2N-64MR-001: 64-point CPU base unit, 32 DC inputs / 32 relay outputs, expandable to 256 I/O.
• FX2N-128MR-001: 128-point CPU base unit, maximum onboard I/O configuration in the FX2N family.

Positioning & High-Speed Counter Modules

• FX2N-1PG: Single-axis pulse output positioning module, 100 kpps max output, supports trapezoidal acceleration profiles.
• FX2N-10PG: Single-axis advanced positioning module, 1 Mpps max, absolute/incremental positioning, JOG operation.
• FX2N-1HC: 1-channel high-speed counter module, 50 kHz max count frequency, phase A/B quadrature input.

Sourcing Hard-to-Find & Obsolete FX2N Parts

With Mitsubishi Electric having ceased FX2N production, procurement of modules such as the FX2N-4AD, FX2N-8AD, FX2N-4DA, and FX2N CPU base units now depends entirely on secondary market channels. DriveKNMS maintains a dedicated inventory of new-old-stock (NOS), refurbished, and tested-serviceable FX2N components sourced from decommissioned plant equipment, authorized distributor overstock, and controlled factory surplus.

For facilities operating FX2N-based control systems beyond the OEM support window, DriveKNMS provides lifecycle extension services including: direct module replacement with tested equivalents, cross-reference mapping to FX3U/FX5U migration paths where full replacement is required, and long-term consignment stocking agreements for maintenance departments with recurring demand. All sourced units are accompanied by full traceability documentation and test records.

Quality Control for the FX2N Range

FX2N modules present specific test challenges due to their FROM/TO instruction-based communication interface, which requires an active FX2N CPU to validate analog channel calibration and digital I/O response. DriveKNMS operates a dedicated FX2N test bench comprising FX2N-128MR-001 base units with GX Developer and GX Works2 programming environments, enabling functional verification of all expansion module types.

Test procedures for the FX2N-4AD specifically include: channel-by-channel input range verification (voltage and current modes), offset/gain register validation via BFM #0–#24 read/write cycles, conversion speed confirmation (15 ms per channel), and isolation resistance measurement between analog commons and chassis ground. Relay output modules (FX2N-16EYR, FX2N-32ER) undergo contact resistance measurement and rated-load switching endurance tests. Communication modules are validated against live Modbus RTU and CC-Link network segments before dispatch.