Mitsubishi FX2N-8EX 8-Point Input Module

Description

Product Introduction & Engineering Value

The FX2N-8EX is a straightforward but useful legacy MELSEC-F expansion module: eight additional discrete inputs, 24 VDC sensing, and a compact terminal-block interface. It connects downstream of a compatible FX-series main unit or extension unit and does not require a separate external power supply for its basic extension-block operation.

For replacement work, the exact suffix matters. Mitsubishi lists the standard FX2N-8EX separately from variants such as FX2N-8EX-ES/UL and FX2N-8EX-UA1/UL. Those versions do not have identical input characteristics, so the original nameplate should be matched before ordering.

Technical Specifications

These values are from Mitsubishi Electric’s published FX2N-8EX specifications.

Compatibility Notes

The FX2N-8EX is documented for connection to several FX-series PLC families. For connector-type PLCs, Mitsubishi specifies additional interface requirements in certain configurations—for example, the FX2NC-CNV-IF is required for FX1NC/FX2NC connections, while FX3GC/FX3UC installations may require the FX2NC-CNV-IF or FX3UC-1PS-5V depending on the configuration.

Field Application & the “Trench” Experience

The FX2N-8EX typically earns its keep when an existing machine has run out of discrete input capacity. A maintenance team may need several additional proximity switches, limit switches, pushbuttons, or interlock contacts without replacing the existing FX-series controller.

The catch is wiring polarity. The standard FX2N-8EX is a sink-input module accepting 24 VDC signals, including no-voltage contacts and NPN open-collector transistor inputs. Installing the wrong FX2N-8EX variant can therefore create a wiring problem even though the module appears physically compatible.

Typical applications include:

1. Packaging-machine limit and photoelectric sensor inputs
2. Conveyor interlock and position detection
3. Machine-tool auxiliary discrete inputs
4. Material-handling equipment with expanded FX-series I/O

FX2N-8EX

FX2N-8EX

Transparency SOP: QA & Testing

For New Surplus or Refurbished FX2N-8EX inventory:

Identification

• Confirm exactly.
• Check the suffix and nameplate.
• Record serial number and manufacturing information where available.

Electrical inspection

• Inspect the M3 terminal block and extension connector.
• Check for cracked terminals, corrosion, contamination, and damaged housing.
• Verify the input circuits using a controlled 24 VDC test source.

Functional test

1. Power the module through a compatible Mitsubishi PLC/extension configuration.
2. Apply the correct 24 VDC input signal to each channel.
3. Verify all eight input LEDs.
4. Confirm that all eight corresponding PLC input devices are recognized.
5. Check for abnormal response, intermittent channels, or excessive input current.

Mitsubishi specifies approximately 10 ms input response time and photocoupler isolation, making channel-by-channel functional testing preferable to a simple visual inspection.

The Veteran’s Tech Trap Guide

⚠️ Trap #1 — Confusing with -UA1.
The standard FX2N-8EX uses 24 VDC inputs. Mitsubishi also offers an FX2N-8EX-UA1 variant for 100 VAC input applications. They are not interchangeable from a wiring perspective.

⚠️ Trap #2 — Forgetting that the standard unit is sink input.
The standard FX2N-8EX accepts NPN/open-collector and no-voltage-contact input arrangements. Confirm the machine’s sensor wiring before replacement.

⚠️ Trap #3 — Assuming every FX connector installation is direct.
Some connector-type FX PLC configurations require an interface converter or power-supply accessory. Check the specific PLC model before installation.

PRO TIP: When replacing an FX2N-8EX, photograph the terminal wiring before removing the old module. The eight input channels are simple, but an undocumented common-terminal arrangement can turn a five-minute replacement into a troubleshooting exercise.

Dynamic FAQ

What is the Mitsubishi FX2N-8EX?

It is an 8-point discrete input extension block for Mitsubishi MELSEC-F FX-series PLCs.

What input voltage does FX2N-8EX use?

The standard FX2N-8EX uses 24 VDC ±10% input signals, with approximately 5 mA per input at 24 VDC.

Is FX2N-8EX a sinking or sourcing input module?

The standard model is a sink-input module. It supports no-voltage contact inputs and NPN open-collector transistor inputs.

How many inputs does it provide?

It provides 8 input points. Mitsubishi specifies a vertical M3 screw terminal block for the standard model.

Is FX2N-8EX still available?

Mitsubishi’s current product information lists the FX2N-8EX as scheduled for discontinuation, with an order end date of March 2028 and production discontinuation in September 2028. Repair support is listed through September 2035, although regional availability can differ.

Is New Surplus FX2N-8EX acceptable?

Yes. For a legacy machine, New Surplus can be a sensible spare strategy. Verify the exact model/suffix, inspect the terminal and extension connectors, and preferably perform an eight-channel functional test before placing the unit into critical service.

What warranty should I request?

Request written coverage for all eight input channels, input LED operation, connector integrity, and operation in the intended FX-series configuration. For refurbished stock, ask whether each input was actually tested or whether the unit only passed a power-up inspection.