Mitsubishi MELSEC FX0N Series Modules: FX0N-16EX

Technical Dossier

Product Details And Specifications

Mitsubishi MELSEC FX0N Series Technical Notes

The Mitsubishi MELSEC FX0N series is a compact, high-density programmable logic controller platform engineered for space-constrained industrial automation environments. Deployed extensively across chemical processing plants, water treatment facilities, automotive assembly lines, and light manufacturing operations throughout Asia, Europe, and the Americas, the FX0N platform established a benchmark for sub-compact PLC architecture in the 1990s and early 2000s. Its modular extension bus allows a single CPU unit to expand I/O capacity up to 128 points, making it a cost-effective backbone for distributed control panels in facilities where DIN-rail space is at a premium. Despite its age, the FX0N series remains active in legacy installations at refineries, packaging lines, and building automation systems where full system replacement is not economically viable.

The Evolution of FX0N Architecture

The FX0N series was introduced by Mitsubishi Electric as a successor to the FX0 platform, inheriting the same compact form factor while expanding program memory capacity and I/O extension capability. The original FX0 supported a maximum of 60 I/O points with no analog capability; the FX0N extended this to 128 digital I/O points and introduced analog extension modules for the first time in this size class. Communication options were limited at launch to RS-422 via the programming port, with optional RS-232C and RS-485 adapters added through the FX0N-232ADP and FX0N-485ADP accessories.

The FX0N CPU units use a proprietary backplane-less architecture: extension modules connect via a direct edge-connector bus on the right side of the CPU or preceding extension unit. This daisy-chain topology means module sequencing is fixed by physical position, a constraint that differentiates FX0N from later FX3U/FX5U platforms which support flexible rack-based I/O assignment. Ladder logic programs are stored in EEPROM (no battery required for program retention), though data registers require a backup battery for retention during power loss. The instruction set is a subset of the MELSEC FX family instruction set, fully compatible with GX Developer and GX Works2 programming environments.

Mitsubishi Electric officially discontinued the FX0N series from active production. The platform has transitioned to end-of-life status, with the FX3G, FX3U, and FX5U series designated as functional replacements. However, direct hardware substitution is not plug-and-play: the FX3G uses a different extension bus connector standard, and I/O wiring terminal layouts differ between generations. For sites running FX0N hardware, spare module procurement remains the most operationally practical maintenance strategy.

FX0N Full Catalog & Functionalities (SKU List)

CPU Units

• FX0N-24MR-ES/UL: 24-point relay output CPU, 14 DI / 10 DO, 2K step program memory, AC power supply.
• FX0N-24MT-ESS/UL: 24-point transistor sink output CPU, 14 DI / 10 DO, high-speed pulse output capable.
• FX0N-40MR-ES/UL: 40-point relay output CPU, 24 DI / 16 DO, expanded base I/O for mid-size panels.
• FX0N-40MT-ESS/UL: 40-point transistor sink output CPU, 24 DI / 16 DO, supports 2-axis pulse output.
• FX0N-60MR-ES/UL: 60-point relay output CPU, 36 DI / 24 DO, maximum onboard I/O in the FX0N CPU range.
• FX0N-60MT-ESS/UL: 60-point transistor sink output CPU, 36 DI / 24 DO, high-speed counter support.

Digital Input Extension Modules

• FX0N-8EX: 8-point 24VDC digital input extension module, sink/source compatible.
• FX0N-16EX: 16-point 24VDC digital input extension module, sink/source compatible, 5VDC bus powered, DIN-rail mount. Extends system input capacity by 16 points per unit.
• FX0N-8EX-ES/UL: 8-point digital input extension, UL-listed variant for North American installations.

Digital Output Extension Modules

• FX0N-8EYR: 8-point relay output extension module, 250VAC/30VDC, 2A per point.
• FX0N-8EYT: 8-point transistor sink output extension module, 24VDC, 0.5A per point, high-speed capable.
• FX0N-8EYT-ESS: 8-point transistor source output extension, for PNP-type field devices.
• FX0N-16EYR: 16-point relay output extension module, 250VAC/30VDC, 2A per point.
• FX0N-16EYT: 16-point transistor sink output extension module, 24VDC, 0.5A per point.

Analog Extension Modules

• FX0N-3A: Combined 2-channel analog input (0–10V / 4–20mA) and 1-channel analog output module, 8-bit resolution.

Communication & Special Function Modules

• FX0N-232ADP: RS-232C communication adapter, connects to CPU programming port for HMI or serial device interfacing.
• FX0N-485ADP: RS-485 communication adapter, supports MELSEC protocol and Modbus RTU for multi-drop network configurations.
• FX0N-CNV-IF: Interface converter block, required for connecting FX2N extension modules to an FX0N CPU bus.

Sourcing Hard-to-Find & Obsolete FX0N Parts

Q: Can you support multi-unit or repeat RFQ requests?
A: Yes. Send the model list, target quantity and destination so DRIVEKNMS can review sourcing options and quote the requirement as a project RFQ.

Quality Control for the FX0N Range

FX0N extension modules communicate with the CPU via a 5VDC parallel extension bus. Failure modes specific to this architecture include bus connector pin oxidation, EEPROM data corruption on CPU units, and relay contact wear on output modules. DriveKNMS applies the following verification procedures to all FX0N units prior to dispatch: visual inspection of PCB and connector pins for corrosion or mechanical damage; powered bus communication test using a reference FX0N CPU to confirm module recognition and I/O point response; functional I/O point test cycling all input channels (for EX modules) or output channels (for EY modules) under load; and for CPU units, full program write/read cycle verification and high-speed counter function test. Relay output modules are tested for contact resistance and switching cycle integrity. Units that do not pass all test stages are not listed for sale.