The FX3G-14MR/ES-A is Mitsubishi Electric’s 14-point relay output base unit for the MELSEC FX3G compact PLC series — the entry-level tier of Mitsubishi’s third-generation FX compact PLC family — providing 8 digital inputs and 6 relay contact outputs in a self-contained AC-powered controller for small standalone machine control, equipment monitoring, and simple automation tasks where the full capability of the FX3U is not required and lowest system cost is the primary specification driver. As the smallest relay output model in the FX3G range, the FX3G-14MR/ES-A delivers fundamental PLC functionality — relay output versatility for direct AC and DC load switching, built-in RS-422 communication, real-time clock, and a 32,000-step program memory — in the most compact and economical FX3G housing. In stock at Atlantech Drives. Request your quote within 24-48 hours with worldwide shipping and 12-month warranty.
What Is the FX3G-14MR/ES-A?
The FX3G-14MR/ES-A is a MELSEC FX3G series compact PLC base unit providing 8 input points (X0–X7) and 6 relay contact output points (Y0–Y5), powered by 100–240 VAC mains supply with an integrated power supply. The FX3G CPU operates at 0.21 µs per basic instruction — slightly slower than the FX3U’s 0.065 µs — with a 32,000-step program memory (half the FX3U’s 64,000 steps) and supports ladder diagram and basic structured programming via GX Works2. The relay outputs are rated at 2 A per contact at 240 VAC, enabling direct control of solenoid valves (via intermediate relay), contactors, and indicator lamps without external interface hardware. Built-in high-speed counter inputs (2 channels at 10 kHz) and pulse output capability (Y0 at 100 kHz) are included despite the entry-level classification, providing basic positioning capability for simple stepper motor applications. The FX3G-14MR/ES-A expands via FX3G extension modules (up to 128 total I/O) and connects to FX3G-compatible left-side special adapters for analogue and communication expansion — though the FX3G adapter range is smaller than the FX3U’s.
Key Technical Specifications
- Model: FX3G-14MR/ES-A
- Total I/O Points: 14 (8 inputs + 6 outputs)
- Input Type: 24 VDC sink (X0–X7)
- Output Type: Relay contact (Y0–Y5), 2 A per point, 240 VAC / 30 VDC
- Power Supply: 100–240 VAC, 50/60 Hz
- Program Memory: 32,000 steps
- Execution Speed: 0.21 µs per LD instruction
- Built-in High-Speed Counters: 2 inputs (10 kHz maximum)
- Built-in Pulse Output: Y0 up to 100 kHz
- Communication: RS-422 (built-in)
- Real-Time Clock: Built-in
- Battery Backup: Yes (program and latch data retention)
- Expansion: Up to 128 total I/O via FX3G extension modules
- Operating Temperature: 0°C to 55°C
- Dimensions (W × H × D): 60 mm × 90 mm × 75 mm
- Weight: Approx. 0.40 kg
Series Comparison & Selection Guide
The MELSEC FX3G and FX3U series occupy different positions in Mitsubishi’s compact PLC hierarchy. The FX3G is the entry-level range — simpler, lower cost, and with a smaller feature set — while the FX3U is the full-featured range with faster CPU, larger memory, and a wider adapter and expansion ecosystem. Key differences relevant to the FX3G-14MR/ES-A versus the FX3U-16MR/ES-A: the FX3G has 0.21 µs instruction execution versus 0.065 µs for FX3U (3× slower), 32,000 steps program memory versus 64,000 steps, 2 high-speed counter inputs versus 6, and a more limited left-side adapter range (no FX3U-20SSC-H SSCNET III/H servo adapter compatibility on FX3G). The FX3G-14MR/ES-A’s 14-point I/O count provides 8 inputs and only 6 outputs, versus 8 inputs and 8 outputs in the FX3U-16MR/ES-A — the 6-output limitation of the 14-point FX3G model reflects the smallest housing size. For applications requiring 6 or fewer relay outputs with 8 inputs and the lowest possible system cost, the FX3G-14MR/ES-A is the correct choice. For applications needing higher execution speed, larger memory, more than 6 outputs from the base unit, or access to the full FX3U adapter range, specify the FX3U-16MR/ES-A instead.
Troubleshooting Guide
If the FX3G-14MR/ES-A fails to power up, verify the AC input voltage at terminals L and N is within the 85–264 VAC operating range using a multimeter — voltages below 85 VAC prevent startup, and voltages above 264 VAC risk damage to the internal power supply. Check that L and N terminals are not reversed and that earth ground (PE) is connected — missing earth ground can cause excessive leakage current that trips upstream RCD/GFCI protection. If the POWER LED illuminates but no input or output activity is observed, check the RUN/STOP switch or link wiring if a hardware RUN switch is configured — some FX3G installations use a physical switch that may have been left in STOP position. For individual output relay contacts that fail to activate despite the Y output being ON in GX Works2’s device monitor, force the output ON from GX Works2 with the machine in a safe state and measure the voltage across the relay contact terminals with a multimeter — a contact showing more than 1 V drop at rated current has reached end of mechanical life and the base unit should be replaced. For high-speed counter inputs reading inconsistently, verify that the input signal’s voltage level matches the FX3G input circuit requirements (24 VDC, 4 mA minimum current) — signals with slow rise times or intermediate voltages can cause unreliable high-speed counter operation at frequencies above 5 kHz.
Frequently Asked Questions
Q: Can the FX3G-14MR/ES-A be programmed with the same GX Works2 software used for FX3U programming?
A: Yes. GX Works2 supports both FX3G and FX3U programming within the same software environment — select the FX3G CPU type when creating a new project for FX3G programming. The ladder instruction set is largely common between FX3G and FX3U, so engineers familiar with FX3U programming can transition to FX3G without significant retraining. However, some FX3U-specific instructions and functions (such as those requiring the FX3U’s faster CPU or larger memory) are not available on the FX3G — GX Works2’s compilation check identifies any compatibility issues.
Q: What is the maximum total I/O achievable with the FX3G-14MR/ES-A?
A: The FX3G-14MR/ES-A supports expansion to a maximum of 128 total I/O points (base unit + extension modules combined). With 14 points on the base unit, up to 114 additional points can be added via FX3G extension I/O units. The 128-point limit is the absolute hardware maximum for the FX3G CPU’s I/O address space — systems requiring more than 128 I/O points must specify the FX3U or FX5U platform.
Q: Does the FX3G-14MR/ES-A support Ethernet communication?
A: The FX3G-14MR/ES-A does not include a built-in Ethernet port. The FX3G platform supports Ethernet via the FX3G-ENET-ADP Ethernet adapter module (if compatible with the base unit model — verify compatibility in Mitsubishi’s FX3G hardware manual). For built-in Ethernet as standard, specify the FX5U series compact PLC, which includes a 100BASE-TX port in the base unit.
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