Mitsubishi Electric FX2N-128MR-ES/UL FX2N Series PLC Base Unit

Executing high-density control sequences across manufacturing lines, the Mitsubishi Electric FX2N-128MR-ES/UL functions as the primary processing base unit within the legacy MELSEC FX2N architecture. This controller integrates processing, power supply, and extensive digital I/O within a single compact chassis, making it a reliable choice for medium-to-large industrial automation applications requiring robust relay outputs and high-speed execution.

Key Features

• Integrated 128 local I/O points (64 inputs and 64 relay outputs) expandable up to 256 points via extension blocks.
• Built-in 100-240V AC power supply with integrated 24V DC auxiliary power output for field sensors.
• Electromechanical relay output contacts rated for 2A per point, allowing direct control of contactors and solenoids.
• High-speed processing capability with a basic instruction execution time of 0.08 microseconds.
• Removable terminal blocks that facilitate rapid field replacement and minimize downtime during maintenance.

Applications

• Conveyor systems and material handling sorting lines.
• Packaging machinery, wrapping stations, and automated assembly lines.
• Water treatment facilities, pump station control panels, and fluid management.
• HVAC systems, environmental control chambers, and building automation.

Technical Specifications

Connections and Interfaces

Alternative Models & Compatibility

The FX2N series is a legacy product line. For modern system retrofits, the FX3U-128MR/ES-A serves as the direct physical and functional successor. It utilizes the same mounting footprint and terminal block layout, though program conversion via GX Works2 or GX Developer is required to compile the legacy FX2N instruction set to the newer FX3U architecture.

Application Pitfalls & Engineering Notes

Inductive loads such as solenoids, contactor coils, and magnetic valves generate significant back-EMF when switched off. To prevent premature contact welding and contact resistance degradation on the internal relays, always install external RC suppressors for AC loads or flyback diodes for DC loads. Additionally, ensure the total current drawn from the auxiliary 24V DC terminal does not exceed 460 mA, as overloading this terminal will trigger the internal overcurrent protection and shut down the input circuits.

Commissioning & Wiring Tips

When wiring the digital inputs, configure the S/S terminal based on your sensor type. Connect the S/S terminal to the 24V terminal for Sink input configuration (NPN sensors) or to the 0V terminal for Source input configuration (PNP sensors). Avoid running I/O signal cables in the same conduit or wire duct as high-voltage power lines to prevent electromagnetic interference from corrupting the input signals.

Installation Guidelines