Mitsubishi PLC Module FX3U-32MRES-A FX3U32MRESA FX3U-32MR/ES-A

Mitsubishi FX3U-32MR/ES-A | MELSEC FX3U 32-Point Compact PLC — 16 DI / 16 DO Relay / 100–240V AC / 64K Steps

FX3U — The Capability Step Above FX2N in a Compact Format

The FX3U is Mitsubishi's highest-performance compact PLC in the MELSEC-F series. The FX3U-32MR/ES-A packs 16 digital inputs and 16 relay outputs into a single compact body with 100–240V AC power supply — the ES-A designating European-standard AC power supply configuration. The unit runs from single-phase AC mains across the full 100–240V range without range selection, covering installations from 100V Japanese grid to 230V European mains without hardware change.

The relay output format switches field loads at AC or DC voltages — contactors, solenoid valves, pilot lights, and small AC motors. For high-frequency switching applications, the transistor output variant (FX3U-32MT) is more appropriate; relay outputs handle industrial load types that require the electrical isolation and voltage flexibility that transistor outputs cannot provide.

Expansion up to 256 I/O points uses FX3U series extension modules and adapters. The FX3U-1PG positioning block, FX3U-4AD analogue input module, and communication adapters for RS-232C, RS-485, and Ethernet all connect to the same base unit, scaling the system from a standalone 32-point controller to a multi-function machine controller without changing the CPU.

Key Specifications

High-Speed Counter at 100 kHz — Without External Hardware

The FX3U-32MR/ES-A includes 6 built-in high-speed counter channels. Four channels operate at 10 kHz; two at 100 kHz. These accept encoder, proximity sensor, or pulse output directly — enabling position tracking, frequency measurement, and speed monitoring within the base unit. For single-axis positioning that requires more structured motion control, the FX3U-1PG positioning block adds dedicated 200 kHz pulse output on top of the base unit's built-in counter functions.

FAQ

Q1: What does the relay output mean in practice compared to a transistor output version?

Relay outputs (MR) switch AC and DC loads at a wide range of voltages — up to 250V AC and 30V DC. The contacts have no fixed polarity requirement. Transistor outputs (MT) switch 24V DC only, but switch faster (no mechanical delay), handle higher cycle rates, and do not wear from contact arcing. Choose relay for AC loads, field devices at voltages other than 24V DC, and lower-frequency switching. Choose transistor for high-frequency pulse output and fast-switching 24V DC loads.

Q2: Can the FX3U-32MR/ES-A be programmed using GX Works3?

The FX3U series is programmed using GX Works2. GX Works3 supports the FX5U and FX5UC (iQ-F series) but not the FX3U generation. Use GX Works2 with the SC09 RS-422 programming cable or a USB adapter for connection to the built-in RS-422 port.

Q3: What expansion modules can connect to the FX3U-32MR/ES-A?

The FX3U accepts standard I/O extension modules (FX2N-EX, FX3U-EX), special function modules (analogue, positioning, communication), and FX3U ADP (expansion adapter) series. The total I/O expands to 256 points maximum. Up to 8 FX3U-1PG positioning blocks can connect for multi-axis motion.

Q4: Does the FX3U-32MR/ES-A have a built-in Ethernet port?

No. The base unit has a built-in RS-422 port for programming and serial communication. For Ethernet connectivity, add the FX3U-ENET-ADP (Ethernet adapter) to the ADP port on the left side of the CPU. The FX3U also supports RS-232C and RS-485 via communication adapters.

Q5: How long is the battery service life, and what data does it protect?

The FX3U uses a built-in lithium battery to retain the user programme in RAM when power is removed. Battery service life is typically 5 years under normal operating conditions. When the battery alarm (M8006) activates, replace the battery within the time specified in the FX3U hardware manual to avoid programme loss.