Mitsubishi FX-4AD – 4-Channel Analog Input Module | MELSEC FX Series Platform
Engineering Background
The Mitsubishi FX-4AD is a dedicated special function module designed for the MELSEC FX Series programmable logic controller family. It enables precise analog signal acquisition in industrial automation environments where accurate process variable monitoring is critical. As part of Mitsubishi Electric’s proven FX platform, the FX-4AD integrates seamlessly with FX1N, FX2N, FX3U, and FX3G base units via the extension bus.
Product Positioning
Targeted at procurement engineers and system integrators in manufacturing, process control, and building automation, the FX-4AD delivers reliable 12-bit analog-to-digital conversion across four independent channels. It is the preferred choice for OEM machine builders requiring compact, DIN-rail-mountable analog front-ends with deterministic scan-cycle performance.
Complete Technical Specifications
| Parameter | Specification |
|---|---|
| Model Number | FX-4AD |
| Manufacturer | Mitsubishi Electric |
| Series / Platform | MELSEC FX Series |
| Number of Channels | 4 (independent) |
| Input Signal Type | Voltage: DC 0–10 V / ±10 V; Current: DC 4–20 mA / 0–20 mA |
| Resolution | 12-bit (1/4096) |
| Conversion Speed | 6 ms / channel (15 ms total for 4 channels) |
| Input Impedance (Voltage) | 200 kΩ |
| Input Impedance (Current) | 250 Ω |
| Accuracy | ±1% of full scale (at 25 °C) |
| Isolation | Photocoupler isolation between channels and PLC bus |
| Power Supply | DC 24 V (supplied via FX extension bus) |
| Current Consumption | 55 mA (DC 5 V from base unit bus) |
| Operating Temperature | 0 °C to +55 °C |
| Storage Temperature | −20 °C to +70 °C |
| Humidity | 5% to 95% RH (non-condensing) |
| Dimensions (W × H × D) | 55 × 90 × 87 mm |
| Weight | Approx. 260 g |
| Mounting | DIN rail / direct panel mount |
| Applicable PLC | FX1N, FX2N, FX2NC, FX3U, FX3UC, FX3G |
| Compliance | CE, UL, cUL |
Proven Application Environments
- Process Control: Temperature, pressure, and flow monitoring via 4–20 mA transmitters
- Machine Automation: Servo drive feedback, tension control, and position sensing
- HVAC & Building Automation: Chiller plant monitoring, VAV box control, CO₂ sensor integration
- Food & Beverage: Filling line weight feedback, pasteurizer temperature loops
- Water Treatment: pH, turbidity, and dissolved oxygen sensor interfacing
- Packaging Machinery: Film tension and web guide analog feedback
Engineering Advantages
- Compact Form Factor: 55 mm wide — minimizes panel footprint in space-constrained enclosures
- Dual-Mode Input: Each channel independently configurable for voltage or current via wiring — no jumper changes required on most FX variants
- High Noise Immunity: Photocoupler isolation prevents ground loops and protects the PLC CPU from field-side transients
- Deterministic Conversion: Fixed 6 ms/channel conversion time ensures predictable scan-cycle budgeting
- Native FX Bus Integration: No external power supply required; powered directly from the FX extension connector
- Long Production History: Proven in millions of installed machines globally; spare parts and replacements readily available
System Architecture & Signal Flow
The FX-4AD connects to the right side of the FX base unit or any FX extension block via the proprietary extension bus connector. Field analog signals are wired to the module’s terminal block (V+/I+/COM per channel). The on-board ADC samples each channel sequentially at 6 ms intervals. Converted digital values are stored in the module’s buffer memory (BFM #0–#3 for current values; BFM #5 for channel enable). The FX CPU reads BFM data using the FROM instruction and writes configuration using the TO instruction. No special function block licensing is required.
Typical Wiring: Field transmitter (+) → CH terminal; Field transmitter (−) → COM terminal. For current input, short the V+ and I+ terminals per channel.
Sourcing & Quality Verification
- All units sourced from authorized Mitsubishi Electric distributors or verified surplus channels with full traceability documentation
- Each module undergoes incoming inspection: visual check, label verification (date code, country of origin), and functional power-on test
- Counterfeit screening: holographic label verification, PCB marking cross-check against Mitsubishi Electric reference samples
- Packaging: anti-static bag + foam insert + original-style carton; shipped with inspection report on request
- Warranty: 12-month replacement warranty against manufacturing defects
Procurement Process
- Confirm Compatibility: Verify your FX base unit model (FX1N / FX2N / FX3U / FX3G) and available extension slots
- Place Order: Add to cart and complete checkout — secure payment via major cards, PayPal, and T/T wire transfer
- Lead Time: In-stock units ship within 1–2 business days; ETA provided at order confirmation
- Documentation: Datasheet, wiring diagram, and FROM/TO programming example available upon request
- After-Sales: Technical support via email or WhatsApp for installation and commissioning queries
Technical FAQ
Q: Can the FX-4AD be used with an FX3U CPU?
A: Yes. The FX-4AD is fully compatible with FX3U and FX3UC base units. Use the FROM/TO instructions or GX Works2 special module wizard for configuration.
Q: How many FX-4AD modules can be connected to one FX base unit?
A: Up to 8 special function modules can be connected to a single FX series base unit, subject to the total extension bus current budget.
Q: What is the difference between FX-4AD and FX3U-4AD?
A: The FX3U-4AD is the next-generation replacement with higher resolution (16-bit) and faster conversion. The FX-4AD (12-bit) remains widely used in legacy machine retrofits and cost-sensitive applications.
Q: Is a 24 V external power supply required?
A: No. The FX-4AD draws its operating power (DC 5 V, 55 mA) directly from the FX extension bus. No separate 24 V supply is needed for the module itself.
Q: Do you provide a certificate of conformance?
A: Yes. A certificate of conformance and incoming inspection report can be provided upon request at no additional charge.
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