Mitsubishi FX3U-32MR/DS CPU Unit

Technical Dossier

Product Details And Specifications

Mitsubishi FX3U Series Technical Notes

The Mitsubishi FX3U series represents the third-generation flagship of Mitsubishi Electric's MELSEC FX compact PLC family. Deployed extensively across global heavy industry — including petrochemical plants, nuclear auxiliary systems, refinery control loops, and automotive assembly lines — the FX3U platform has established a dominant installed base in Asia-Pacific, Europe, and the Americas. Its 32-bit RISC CPU architecture, high-speed pulse output (up to 100 kHz on 6 axes), and native USB programming port made it the de facto standard for standalone machine control from its introduction in 2004 through the mid-2010s. The FX3U-32MR/DS specifically is a 32 I/O relay output CPU unit operating on DC power supply (24 VDC), with 16 inputs and 16 relay outputs, suited for applications requiring isolated output switching in harsh electrical environments.

The Evolution of FX3U Architecture

The FX lineage began with the FX0/FX0N series in the early 1990s, progressing through FX1N, FX2N, and FX2NC before the FX3U was introduced as a high-performance successor. The FX3U retained backward compatibility with FX2N expansion modules via adapter blocks, a critical design decision that protected existing installations. Its successor, the FX5U (introduced ~2014), migrated to Ethernet-native communication and a 64-bit architecture, rendering FX3U a mature/legacy platform. However, the FX3U remains in active production and is supported under Mitsubishi's long-term maintenance policy. Facilities running FX3U-based systems face compatibility constraints when integrating with newer CC-Link IE Field networks, typically requiring gateway modules (e.g., FX3U-ENET-ADP) as bridging solutions. The FX3U-32MR/DS variant uses a DC power supply input, distinguishing it from the FX3U-32MR/ES (AC supply) in the same I/O class.

FX3U Full Catalog & Functionalities (SKU List)

CPU Units

• FX3U-16MR/ES: 16 I/O relay output CPU, AC supply
• FX3U-32MR/DS: 32 I/O relay output CPU, DC 24V supply — current item
• FX3U-32MR/ES: 32 I/O relay output CPU, AC supply
• FX3U-48MR/ES: 48 I/O relay output CPU, AC supply
• FX3U-64MR/ES: 64 I/O relay output CPU, AC supply
• FX3U-80MR/ES: 80 I/O relay output CPU, AC supply
• FX3U-128MR/ES: 128 I/O relay output CPU, AC supply, max base config
• FX3U-32MT/ES: 32 I/O transistor sink output CPU, AC supply
• FX3U-32MT/ESS: 32 I/O transistor source output CPU, AC supply
• FX3U-64MT/ES: 64 I/O transistor sink output CPU, AC supply

Communication & Network Adapters

• FX3U-ENET: Ethernet communication module, 10/100 Mbps, left-side mount
• FX3U-ENET-ADP: Ethernet adapter for FX3U/FX3UC, compact form factor
• FX3U-232ADP-MB: RS-232C adapter with MODBUS RTU master/slave support
• FX3U-485ADP-MB: RS-485 adapter with MODBUS RTU, multi-drop capable
• FX3U-USB-BD: USB function expansion board for programming port

Special Function & Analog Modules

• FX3U-4AD: 4-channel analog input module, 12-bit resolution
• FX3U-4DA: 4-channel analog output module, 12-bit resolution
• FX3U-4AD-PT-ADP: 4-channel PT100 temperature input adapter
• FX3U-4AD-TC-ADP: 4-channel thermocouple input adapter (K/J/T/E/R/S/B)
• FX3U-1PG: Single-axis pulse generator module, 200 kHz max output
• FX3U-20SSC-H: 2-axis SSCNET III servo positioning module