What this unit is and what it isn't
The FX3U-64MT/ESS is a Mitsubishi MELSEC-F series main CPU unit with 32 digital inputs and 32 transistor source outputs. It runs on 100-240 VAC and draws 45 W. That means it needs a dedicated circuit with proper isolation — no sharing a panel tap with high-inrush loads. IP10 protection class means zero sealing against dust or moisture. This unit belongs in a clean, dry enclosure — not on a conveyor near coolant mist. USB is listed as an option, not a standard port. If you need USB for programming, verify the variant or add an adapter.
Lifecycle and sourcing reality
For a line-down replacement, the FX3U-64MT/ESS is specified in thousands of existing panels. Source it to order via RFQ; lead time on this mature part typically runs 1-10 working days.
I/O capacity and expansion
Onboard I/O gives you 32 inputs and 32 source outputs. Expand via the MELSEC-F extension bus to a total of 384 local+remote points — enough for a medium skid or machine cell. Program memory is 64K steps in RAM with a buffer battery. Cycle time is 65 ns for LD, 642 ns for MOV — fast enough for most discrete logic but not for nanosecond-level servo loops.
Does it replace an FX5-C32EYT/D-TS?
The FX5U-64MT/DS is a direct CPU module alternative but with different power supply (24 VDC vs AC) and belongs to a newer series. Panel rewire and program conversion are required.