FX3U-48MT/ES-A is a 48-point transistor output programmable logic controller from Mitsubishi Electric’s MELSEC FX3U series, one of the most widely deployed compact PLC families in industrial automation globally. With 24 DC inputs and 24 transistor (NPN sink) outputs, operating on a 100–240 V AC power supply, this unit provides a high-performance processing platform in a compact DIN-rail form factor. The FX3U-48MT/ES-A supports a program memory capacity of 64,000 steps and a basic instruction execution time of 0.065 µs, positioning it at the top tier of the FX3 generation. Available now at Atlantech Drives with worldwide express delivery and 12-month warranty — complete our quote form for pricing and availability.
What Is the FX3U-48MT/ES-A?
The FX3U-48MT/ES-A belongs to the MELSEC FX3U series, Mitsubishi Electric’s third-generation compact PLC platform. The part number encodes key specifications: «48» indicates the total I/O count (24 inputs + 24 outputs), «MT» identifies the output type as transistor (as opposed to «MR» for relay), «ES» denotes the power supply type as 100–240 V AC with 24 V DC input compatibility, and «A» is a revision suffix. This model’s transistor output type supports pulse output functions up to 100 kHz on designated output channels (Y0, Y1, Y2), enabling direct open-loop stepper motor and servo drive positioning without additional pulse generator modules. The FX3U base unit can be expanded with up to 8 extension modules and 10 special function modules, scaling the I/O count up to 256 points in mixed digital and analogue configurations.
Key Technical Specifications
- Total I/O Points: 48 (24 inputs / 24 outputs)
- Output Type: Transistor NPN (sink), 0.5 A per point, 8 A per common
- Input Voltage: 24 V DC (sink/source selectable)
- Power Supply: 100–240 V AC, 50/60 Hz
- Program Memory: 64,000 steps (Flash ROM)
- Basic Instruction Speed: 0.065 µs/instruction
- Pulse Output: Up to 100 kHz on Y0, Y1, Y2 (independent axes)
- Built-in High-Speed Counters: 6 channels (max. 100 kHz)
- Data Registers: 8,000 (D0–D7999)
- Internal Relay: 3,072 M-relays
- RTC (Real-Time Clock): Built-in
- USB Programming Port: Mini-USB (RS-422 adapter also supported)
- Dimensions (W × H × D): 220 × 90 × 75 mm (approx.)
- Operating Temperature: 0 °C to 55 °C
- Weight: Approx. 650 g
Typical Industrial Applications
The FX3U-48MT/ES-A is widely used across a broad range of industrial sectors due to its combination of processing speed, I/O density, and built-in motion capability. In packaging machinery, the transistor pulse outputs are used to drive stepper indexers for film feeding and sealing jaw positioning, eliminating the cost of a dedicated motion controller. In HVAC and building automation, the AC power supply and generous data register space make the FX3U-48MT/ES-A a natural choice for BMS gateway controllers managing multi-zone valve actuators and variable speed drives via RS-485 Modbus. In food and beverage production lines, its IP20-rated compact body fits into standard stainless enclosures, and the 64k step program memory accommodates complex recipe management routines alongside the I/O sequencing logic. The high-speed counter inputs are frequently used in web tension control systems for encoder feedback from driven nip rollers, while the real-time clock enables time-stamped batch logging to SCADA via the FX3U-ENET or FX3U-ENET-L Ethernet communication modules.
Troubleshooting Guide
The most common field issues encountered with the FX3U-48MT/ES-A relate to three areas: output load faults, communication errors, and memory retention. For output faults, transistor outputs Y0–Y17 can be damaged by inductive loads without suppression diodes — always fit a flyback diode or RC snubber across relay coils and solenoids driven by these outputs. If the ERROR LED illuminates at startup, connect GX Works2 or GX Works3 and check the Special Auxiliary Relay SM0 (Run) and the error code stored in SD0/SD1; the most frequent cause is a sum check error in program memory, resolved by a full program clear and reload from the engineering PC. For USB communication issues on Windows 10/11, ensure the USB driver version is 1.20 or later (available from Mitsubishi’s FA Global Website) — older drivers cause COM port enumeration failures under newer Windows builds. If the RTC loses time after a power cycle, replace the internal lithium battery (Mitsubishi part Q6BAT or equivalent CR2032-class cell) — the expected battery life is approximately 5 years under normal operating conditions.
Frequently Asked Questions
Q: Can the FX3U-48MT/ES-A control servo drives directly without a positioning module?
A: Yes. Outputs Y0, Y1, and Y2 support pulse train output up to 100 kHz, allowing direct connection to servo amplifiers in pulse/direction or CW/CCW input mode. For more sophisticated motion profiles (S-curve acceleration, simultaneous multi-axis interpolation), Mitsubishi recommends adding the FX3U-20SSC-H positioning module, which offloads trajectory calculation from the CPU.
Q: What is the difference between FX3U-48MT/ES-A and FX3U-48MT/ESS-A?
A: The ESS variant includes a built-in CC-Link/LT slave interface, enabling the unit to be deployed as a remote I/O station on a CC-Link/LT network without an additional communication module. The standard ES-A variant does not include this interface and communicates via its USB/RS-422 programming port and optional add-on communication modules such as FX3U-485BD or FX3U-ENET-L.
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