Mitsubishi Electric FX2N-128MR-001 MELSEC FX2N Series PLC Main Unit

Description

Managing up to 128 local I/O points, the Mitsubishi Electric FX2N-128MR-001 serves as a high-density controller within the legacy MELSEC FX2N micro-PLC architecture. This base unit integrates 64 digital inputs (24V DC, sink/source selectable) and 64 relay outputs in a single, space-efficient housing, providing a reliable point of control for high-I/O machinery and assembly lines. Designed to support modular expansion, the unit accommodates FX2N series extension blocks, analog modules, and communications adapters to scale control system capabilities as process demands evolve.

Features

• All-in-One High-Density Control: Packs 128 physical input/output terminals in one chassis, reducing cabinet space requirements.
• Flexible Input Configuration: Configurable for sink or source logic via a simple hardware terminal connection.
• Robust Relay Outputs: Dry contact relay outputs support up to 2A per channel for switching AC or DC control circuit loads.
• Expandable Architecture: Built-in bus interface allows seamless connection of additional digital and functional expansion blocks.
• Program Memory Cassette Support: Includes a slot for optional EEPROM or Flash memory cassettes for easy program backup and transfer.

Applications

• Material Handling Systems: Conveyor sorting, palletizer control, and multi-station transfer tables.
• Packaging Machinery: Multi-lane filling, form-fill-seal machines, and heavy carton sealing plants.
• Automotive Assembly Cells: Coordinating pneumatic actuators, rotary tables, and localized safety interlocks.
• Municipal Water Management: Multi-pump control stations with auxiliary monitoring elements.

Technical Specifications

Terminal Layout & Circuit Configuration

Alternative Models & Compatibility

The FX2N series is a legacy line. When updating systems utilizing the FX2N-128MR-001, the direct, modern replacement from Mitsubishi Electric is the FX3U-128MR/ES-A. While the FX3U model features structural and dimension alignment for easy retrofitting, there are critical considerations:

• Program Migration: Legacy programs from FX2N can be converted to FX3U format inside GX Developer or GX Works2/3 software. Be sure to review instruction sets since execution times on FX3U are significantly faster, which can impact legacy software-timed loops.
• Terminal Block Wiring: Terminal block layouts are nearly identical, but terminal pitch and physical width of the modules should be cross-verified before swapping to ensure panel depth clearing.

Application Pitfalls & Engineering Notes

• Relay Contact Derating: Inductive AC loads (solenoids, contactors) create large voltage spikes at drop-out. For maximum relay lifetime, install surge absorbers (RC networks) parallel to the load. For DC inductive loads, always install a freewheeling diode.
• Thermal Management: In enclosed control panels, always mount this high-I/O unit horizontally to ensure convective airflow. Vertical mounting restricts airflow and can lead to premature thermal degradation of the internal power supply module.
• Inrush Current: The 100-240V AC power supply block has an inrush current rating that can reach up to 40A at peak. Ensure upstream circuit breakers are sized with a suitable delay curve to prevent nuisance tripping on power-up.

Installation Guidelines