FZ0430 voltage sensor module with Arduino-based PLC: wiring and sketch

The FZ0430 is a resistive voltage divider module that scales DC voltages up to 25 V down to the 0–5 V range readable by an Arduino analog input. Connecting one to an Arduino-based PLC gives you direct voltage monitoring with no additional signal conditioning — useful anywhere you need to track DC bus voltage, battery state, or panel output without breaking the circuit.

This post covers the module specifications, wiring to an M-Duino PLC, and a working Arduino sketch that converts the raw ADC reading to the actual measured voltage.

FZ0430 specifications

The module applies a fixed voltage divider: Vout = Vin × R2 / (R1 + R2) = Vin / 5. Reversing this in the sketch gives the actual input voltage: Vin = Vout × 5.

Requirements

• Arduino-based PLC with analog inputs (M-Duino 21+, 42+, 58+, or Ardbox Analog)
• FZ0430 voltage sensor module
• Arduino IDE with the Industrial Shields board library installed
• DC voltage source to measure (battery, bus, panel output — max 25 V)

No additional libraries required.

Wiring

The FZ0430 has two sets of connections: signal pins (VCC, GND, SIG) for the Arduino side, and screw terminals (VIN+, VIN−) for the voltage being measured.

Do not exceed 25 V on the VIN+ terminal. The VIN− terminal must share the same ground reference as the M-Duino.

Arduino sketch

The sketch reads the SIG output, converts it to voltage, then applies the divider ratio to recover the actual input voltage. Adjust DIV_RATIO if you calibrate against a reference meter.

// FZ0430 voltage sensor — Arduino-based PLC
// Reads DC voltage up to 25 V on M-Duino analog input

#define SENSOR_PIN   A0      // I0.12 on M-Duino
#define DIV_RATIO    5.0     // FZ0430 divides input voltage by 5
#define NUM_SAMPLES  50      // Samples to average per reading

void setup() {
  Serial.begin(9600);
}

void loop() {
  long sum = 0;
  for (int i = 0; i < NUM_SAMPLES; i++) {
    sum += analogRead(SENSOR_PIN);
    delay(2);
  }
  float avgADC = sum / (float)NUM_SAMPLES;

  // M-Duino 0–10 V input: full ADC range (0–1023) = 10 V
  float vout = (avgADC / 1023.0) * 10.0;

  // Recover actual input voltage using the divider ratio
  float vin = vout * DIV_RATIO;

  Serial.print("Vout: ");
  Serial.print(vout, 3);
  Serial.print(" V  |  Vin: ");
  Serial.print(vin, 3);
  Serial.println(" V");

  delay(500);
}

The FZ0430 outputs 0–5 V for a 0–25 V input. On the M-Duino 0–10 V analog input, this uses roughly half the ADC range (ADC ≈ 512 at Vin = 25 V). For tighter resolution on a known voltage range, add a software calibration factor against a reference meter.

Industrial use cases

DC voltage monitoring with the FZ0430 applies to a range of field instrumentation tasks:

• Battery state monitoring — track 12 V or 24 V battery voltage on UPS and backup systems
• DC bus monitoring — watch inverter and drive DC bus voltage for out-of-range conditions
• Solar panel output — measure open-circuit and operating voltage per string
• Generator output verification — confirm DC output is within spec before connecting to load
• Power supply health — log voltage drift over time as an early indicator of PSU degradation

For AC voltage measurement, a dedicated AC voltage transducer with 4–20 mA output is the appropriate choice. The FZ0430 is DC only.

Running this on Industrial Shields hardware

The M-Duino and Ardbox families from Industrial Shields are programmable controllers built on original Arduino boards — the same hardware and IDE you are already using. M-Duino PLCs (21+, 42+, 58+) are DIN-rail mounted controllers based on the Arduino Mega, with industrial-grade I/O protection, 12–24 VDC power input, and relay, analog, and digital I/Os ready for panel installation. The Ardbox series brings the same industrial hardening to a more compact form factor based on the Arduino Leonardo.

Both families run standard Arduino sketches without modification. The FZ0430 example above works as-is — wire the module to the analog input, upload via the Arduino IDE, and the PLC reads and reports voltage inside an IP20-rated enclosure ready for industrial cabinet installation.