The FX3U-80MT/ESS is Mitsubishi Electric’s 80-point transistor sink output base unit for the MELSEC FX3U compact PLC series, providing 40 digital inputs and 40 NPN open-collector transistor outputs in a self-contained AC-powered controller — the largest sink transistor output base unit in the FX3U range, combining the high-cycle durability and built-in pulse output capability of transistor outputs with the 80-point I/O density previously only achievable with relay output models or multiple extension units. Designed for demanding high-cycle discrete automation where 40 output points must switch 24 VDC loads at frequencies exceeding relay contact life limits, the FX3U-80MT/ESS eliminates the output contact wear problem while maximising I/O density in a single compact controller. In stock at Atlantech Drives. Request your quote within 24-48 hours with worldwide shipping and 12-month warranty.
What Is the FX3U-80MT/ESS?
The FX3U-80MT/ESS is a MELSEC FX3U series compact PLC base unit with transistor sink (NPN open-collector) outputs, providing 40 input points (X0–X47) and 40 transistor output points (Y0–Y47). It is the NPN sink counterpart to the FX3U-80MT/ES-A source model, sharing the identical CPU architecture, program memory, communication interfaces, and expansion capabilities while differing only in output transistor polarity. The output common terminal connects to the external 24 VDC positive supply, and the NPN output transistors pull individual output terminals to 0 VDC when activated — consistent with PNP sensor and 3-wire PNP output device wiring used in North American automation practice and in many Japanese OEM machine designs. The FX3U-80MT/ESS provides the same built-in 100 kHz pulse output on Y0 and Y1 as all other FX3U transistor output base units, enabling direct 2-axis stepper or servo positioning from the base unit without additional hardware. With 40 transistor outputs providing unlimited electrical cycle life, the FX3U-80MT/ESS is the preferred specification for high-throughput packaging machinery, continuous web processing equipment, and automated test systems where output switching rates would exhaust relay contact life within months of operation.
Key Technical Specifications
- Model: FX3U-80MT/ESS
- Total I/O Points: 80 (40 inputs + 40 outputs)
- Input Type: 24 VDC sink (X0–X47)
- Output Type: Transistor sink/NPN open-collector (Y0–Y47), 0.5 A per point, 5–30 VDC
- Output Polarity: Sink (NPN) — common terminal to +24 VDC positive
- High-Speed Pulse Output: Y0 and Y1 up to 100 kHz; Y2 up to 10 kHz
- Power Supply: 100–240 VAC, 50/60 Hz
- Program Memory: 64,000 steps
- Execution Speed: 0.065 µs per LD instruction
- Built-in High-Speed Counters: 6 inputs (100 kHz)
- Communication: RS-422 (built-in)
- Real-Time Clock: Built-in
- Battery Backup: Yes
- Expansion: Up to 8 extension units, up to 4 special adapters
- Operating Temperature: 0°C to 55°C
- Dimensions (W × H × D): 220 mm × 90 mm × 87 mm
- Weight: Approx. 1.20 kg
Typical Industrial Applications
The FX3U-80MT/ESS is the dominant specification in high-cycle Japanese and North American OEM machine designs requiring 40 or more transistor outputs from a single compact PLC. In high-speed blister packaging machines for pharmaceutical and food products, the FX3U-80MT/ESS controls 24 VDC actuators across the full machine sequence — film forming station heater enable relays, sealing station cylinder solenoids, punching station actuators, reject station diverters, and conveyor belt drive enables — all from a single 80-point controller without extension modules, reducing panel wiring complexity and machine footprint. In automated circuit board assembly equipment, the FX3U-80MT/ESS controls component placement solenoid valves, pick head vacuum generators, camera trigger outputs, and conveyor motor enable signals, all requiring sub-millisecond switching response that relay output models cannot reliably provide at the required cycle rates. Food processing portion control systems use the FX3U-80MT/ESS to activate individual cutting blade solenoids, conveyor lane diverters, and weight-based reject actuators at high cycle rates driven by product flow on multi-lane processing lines. Textile loom controllers use the FX3U-80MT/ESS for individual heddle frame solenoid control, where each of the 40 outputs controls a different weave pattern actuator cycling many thousands of times per hour throughout each production shift.
Maintenance Tips
The FX3U-80MT/ESS transistor outputs have no mechanical wear components, but the output transistors can be degraded by repeated inductive load switching without adequate suppression. Perform a systematic inspection of inductive load suppression components — flyback diodes on relay coils and solenoid valves, MOV suppressors on AC loads connected via intermediate relays — at the annual preventive maintenance interval. For each output point, measure the voltage spike amplitude across the transistor output terminals during load deactivation using a digital oscilloscope with a peak-hold function — the spike should not exceed 30 VDC (the output transistor’s maximum collector voltage). If any output shows spikes above 30 VDC, fit or replace the flyback diode on the corresponding load immediately. Monitor the FX3U-80MT/ESS’s output error register in GX Works2 periodically during operation — the FX3U accumulates output overcurrent events in special auxiliary relays M8028X (output error flag), and a pattern of recurring overcurrent flags on specific output points indicates impending transistor failure on those points before complete output failure occurs. For installations in high-ambient-temperature environments (above 40°C), reduce the maximum simultaneous output count below 40 if all outputs are driving loads at the full 0.5 A rating — consult the FX3U-80MT/ESS derating table in the hardware manual for the allowable simultaneous output count at the installation’s ambient temperature.
Frequently Asked Questions
Q: Can the FX3U-80MT/ESS be directly substituted for the FX3U-80MR/ES-A relay model in an existing installation?
A: The FX3U-80MT/ESS can replace the FX3U-80MR/ES-A mechanically and electrically in most 24 VDC load applications, but cannot directly replace relay outputs controlling AC loads — the transistor outputs are rated for 5–30 VDC only. If the existing installation uses any relay outputs to control 110 VAC or 230 VAC loads directly, those loads must be rewired through intermediate 24 VDC relay modules driven by the FX3U-80MT/ESS transistor outputs. For installations with exclusively 24 VDC loads, the substitution requires only rewiring the output common terminals (from relay group commons to a single transistor common positive) and verifying that all output loads are within the 0.5 A transistor rating.
Q: What is the maximum number of FX3U-80MT/ESS outputs that can be simultaneously ON in a high-ambient-temperature panel?
A: The maximum simultaneous ON output count depends on the ambient temperature and the load current per point. At 55°C ambient with 0.5 A per output (maximum rated current), the FX3U hardware manual specifies a derating — typically a maximum of 20 simultaneous ON points at full rated current in the worst-case thermal condition. At lower load currents (0.1–0.2 A per point, typical for solenoid valves), all 40 outputs can be simultaneously ON up to 55°C ambient. Consult the FX3U-80MT/ESS hardware manual’s thermal derating table (Section 2, I/O specifications) for the precise simultaneous ON count limit at the installation’s operating temperature and load current.
Q: Can the FX3U-80MT/ESS generate independent pulse outputs on Y0 and Y1 simultaneously for 2-axis positioning?
A: Yes. The FX3U-80MT/ESS supports simultaneous 2-axis pulse output on Y0 and Y1 using the DRVI/DRVA instructions for independent axis moves or by executing simultaneous PLSY instructions on both axes. Each axis generates its pulse train independently — Y0 can be running a positioning move at a different speed and remaining distance from Y1 simultaneously. The two axes do not perform interpolated coordinated moves natively in the FX3U-80MT/ESS — for true linear interpolation between Y0 and Y1, the FX3U-20SSC-H special adapter module must be used.
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