# MPINO-8A4R-SU

MPINO-8A4R-SU is an all-in-one industrial Arduino with 8 digital inputs and 4 relay with independent COM terminals outputs. A single PCB integrates selectable analog inputs, NTC temperature sensor inputs, 6 PWM outputs, and RS-485·I²C·SPI communication.

Program the controller with Arduino IDE (Arduino C/C++) or MPINO STUDIO 2 (Arduino C/C++ & ladder logic).

See the [MPINO Series specifications](https://www.ilogics.net/docs/en-us_products:mpino_series#mpino_series_specifications "en-us_products:mpino_series") for the board name, connection method, and first I/O numbers for MPINO-8A4R-SU.

![MPINO-8A4R-SU connector guide ](https://www.ilogics.net/docs/_media/en-us_products:mpino-8a4r-su-connectors.svg "MPINO-8A4R-SU connector guide ")

## Product Specifications

| Category | Quantity | Terminal / Item | Specifications |
| --- | --- | --- | --- |
| Power | - | Supply voltage | DC 24V only (0.5A or more) |
| Digital inputs | 8 points   (Solid-state, isolated) | P0~P7 | operating input voltage: DC 0~40V   HIGH detection voltage: DC 5V or higher   4 points/1COM   NPN/PNP input support |
| Relay outputs | 4 points   (Mechanical contacts, isolated) | P32~P35 | operating connection voltage: DC 0~30V or AC 0~250V   maximum allowable output current: 16A/1 points, 16A/1COM   1 points/1COM |
| Analog inputs | 4 points   (Non-isolated) | A0~A3 | DC 0~5V: 10bit (0~1023), input resistance 100MΩ (±1%)   0~20mA or 4~20mA: 10bit (0~1023 or 0~818), input resistance 250Ω (±1%)   DC 0~10V: 10bit (0~1023), input resistance 200kΩ (±1%), optional |
| Temperature sensor inputs | 2 points   (Non-isolated) | NTEMP   A4, A5 | input temperature: -40~120℃   Sensor: NTC 3950K, 10kΩ(25℃)   Resolution: 0.1℃ (at 0~40℃) |
| Interrupts   High-Speed Counter / Encoder | 4 points   (Non-isolated) | D24(CLK), D25(DIO)   D18(SCL), D19(SDA) | input voltage: DC 0~5V   HIGH detection voltage: DC 3V or higher   input frequency: Max. 50kHz   Built-in 10kΩ pull-up   FND unavailable when D24/D25 are in use   I²C unavailable when D18/D19 are in use |
| Pulse outputs | 6 points   (Non-isolated) | PWM   D21, D22, D23   D26, D27, D28 | output voltage: LOW(DC 0V), HIGH(DC 5V)   maximum output current: 30mA |
| Communication Channels | 1 channel   (Non-isolated) | I²C | I²C master/slave supported   Can be used as interrupt ports (10kΩ pull-up) |
| SPI | SPI master/slave supported   No pull-up or pull-down |
| RS-485 | Uses Serial1   Built-in Modbus RTU Master & Slave commands supported   Built-in LS Industrial Systems Cnet commands supported |
| Memory | - | Flash | 128KB |
| SRAM | 4KB |
| EEPROM | 4KB |

## Digital inputs

[See the one-channel digital-input check before wiring for the first time. →](https://www.ilogics.net/docs/en-us_guide:wiring#digital_input_one_channel_check "en-us_guide:wiring")

| Terminal | Arduino Pin | Input Configuration | Terminals and Wiring Example |
| --- | --- | --- | --- |
| P0~P3 | D0~D3 | 4 digital inputs, sharing COM0 | [MPINO-8A4R-SU digital input terminals and NPN/PNP wiring](https://www.ilogics.net/docs/_media/en-us_products:mpino-8a4r-su-digital-input.svg "en-us_products:mpino-8a4r-su-digital-input.svg") |
| P4~P7 | D4~D7 | 4 digital inputs, sharing COM1 |

The digital inputs are isolated by optocouplers and accept DC 5~24V NPN or PNP signals. Select the input type by wiring the COM terminal accordingly.

### Example program · digital inputs

Use digitalRead() to display the D0~D7 input states every 200ms. HIGH is 1 and LOW is 0.

```cpp
void setup() {
  Serial.begin(115200);
}
 
void loop() {
  for (uint8_t pin = 0; pin <= 7; pin++) {
    Serial.print(F("D"));
    Serial.print(pin);
    Serial.print(F(": "));
    Serial.println(digitalRead(pin));
  }
  delay(200);
}
```

**Related built-in functions**

#### Function example · consecutive-read filter: IdigitalRead()

**Function prototype**

```cpp
bool IdigitalRead(uint8_t pin, uint8_t samples);
```

IdigitalRead(0, 5) reads D0 5 times consecutively. It updates the state when all readings are HIGH or all are LOW; mixed readings retain the previous state. Unlike a time-based debounce filter, it inserts no delay between readings.

```cpp
void setup() {
  Serial.begin(115200);
}
 
void loop() {
  const bool inputOn = IdigitalRead(0, 5);  // Read D0 five times consecutively and return the stable state
  Serial.println(inputOn ? F("D0 ON") : F("D0 OFF"));
  delay(200);
}
```

#### Function example · debouncing: Ibounce(), IbounceOn(), IbounceOff()

**Function prototype**

```cpp
bool Ibounce(uint8_t pin, uint32_t debounceTime);
bool IbounceOn(uint8_t pin, uint32_t debounceTime);
bool IbounceOff(uint8_t pin, uint32_t debounceTime);
```

Compare three filters on the D0 input. Each returns the filtered ON/OFF state.

- `Ibounce(0, 30)`: Apply either ON or OFF after it remains stable for at least 30ms.
- `IbounceOn(0, 500)`: Delay ON by 500ms; apply OFF immediately.
- `IbounceOff(0, 500)`: Delay OFF by 500ms; apply ON immediately.

Each function operates independently, even on the same pin. Run the filters on every loop() iteration and display only the results at 200ms intervals.

```cpp
unsigned long lastPrint = 0;
 
void setup() {
  Serial.begin(115200);
}
 
void loop() {
  const bool stable = Ibounce(0, 30);  // Filter D0 ON/OFF chatter over 30ms
  const bool onDelayed = IbounceOn(0, 500);  // Delay only D0 ON by 500ms; apply OFF immediately
  const bool offDelayed = IbounceOff(0, 500);  // Delay only D0 OFF by 500ms; apply ON immediately
 
  if (millis() - lastPrint >= 200) {
    lastPrint = millis();
    Serial.print(F("Ibounce: "));
    Serial.print(stable);
    Serial.print(F(", IbounceOn: "));
    Serial.print(onDelayed);
    Serial.print(F(", IbounceOff: "));
    Serial.println(offDelayed);
  }
}
```

#### Function example · input toggle: Ialt()

**Function prototype**

```cpp
void Ialt(bool input, bool &state_var);
```

Ialt(input, state) inverts state whenever the input changes from OFF to ON. Pressing D0 once turns D32 ON; pressing again turns it OFF. Holding the input does not change the state again. This example debounces the input with Ibounce(0, 30) before passing it to Ialt(). outputOn is a global variable retained between calls, and Ialt() modifies it directly.

```cpp
bool outputOn = false;
 
void setup() {
  Serial.begin(115200);
  digitalWrite(32, LOW);
}
 
void loop() {
  const bool previous = outputOn;
  const bool inputOn = Ibounce(0, 30);  // Filter D0 ON/OFF chatter over 30ms
  Ialt(inputOn, outputOn);  // Invert outputOn on an OFF→ON input transition
  digitalWrite(32, outputOn ? HIGH : LOW);
 
  if (outputOn != previous) {
    Serial.println(outputOn ? F("D32 ON") : F("D32 OFF"));
  }
}
```

## Relay outputs

[See the one-channel relay-output check before wiring for the first time. →](https://www.ilogics.net/docs/en-us_guide:wiring#relay_output_one_channel_check "en-us_guide:wiring")

| Terminal | Arduino Pin | Contact ratings | COM configuration | Terminals and Wiring Example |
| --- | --- | --- | --- | --- |
| P32 | D32 | AC 250V or DC 30V, Max. 16A | Separate COM2 | [MPINO-8A4R-SU relay output terminals and load wiring](https://www.ilogics.net/docs/_media/en-us_products:mpino-8a4r-su-relay-output.svg "en-us_products:mpino-8a4r-su-relay-output.svg") |
| P33 | D33 | AC 250V or DC 30V, Max. 16A | Separate COM3 |
| P34 | D34 | AC 250V or DC 30V, Max. 16A | Separate COM4 |
| P35 | D35 | AC 250V or DC 30V, Max. 16A | Separate COM5 |

Each relay point has its own independent COM terminal. Relay contacts are dry contacts that do not supply power; relay operation requires a DC 24V supply.

### Example program · relay outputs

Map inputs D0~D3 to outputs D32~D35 in order. When an input is HIGH, its corresponding output turns ON.

```cpp
void setup() {
  for (uint8_t pin = 32; pin <= 35; pin++) digitalWrite(pin, LOW);
}
 
void loop() {
  for (uint8_t ch = 0; ch < 4; ch++) {
    digitalWrite(32 + ch, digitalRead(0 + ch));
  }
}
```

## Analog / Temperature inputs

| channel | Input Type | Input Range | Connector Pinout |
| --- | --- | --- | --- |
| A0~A3 | Selectable analog inputs | DC 0~5V or 0~20mA·4~20mA   DC 0~10V is optional | [MPINO-8A4R-SU analog/temperature input connector pinout](https://www.ilogics.net/docs/_media/en-us_products:mpino-8a4r-su-analog-input.svg "en-us_products:mpino-8a4r-su-analog-input.svg") |
| A4, A5 | NTC temperature sensor inputs | NTC 10kΩ, 3950K |

A0~A3 ship in 0~20mA mode; removing each channel's SELECT jumper enables DC 0~5V input.

### Example program · analog inputs

Use analogRead() to display the ADC raw values (0~1023) of A0~A3. Each channel's voltage/current mode follows the actual product settings.

```cpp
const uint8_t analogPins[] = {A0, A1, A2, A3};
 
void setup() {
  Serial.begin(115200);
}
 
void loop() {
  for (uint8_t ch = 0; ch < 4; ch++) {
    Serial.print(F("A"));
    Serial.print(ch);
    Serial.print(F(" ADC: "));
    Serial.println(analogRead(analogPins[ch]));
  }
  delay(500);
}
```

**Related built-in functions**

#### Function example · input range scaling: IanalogRead(), IanalogReadf()

**Function prototype**

```cpp
int32_t IanalogRead(uint8_t ch, int32_t min, int32_t max);
float IanalogReadf(uint8_t ch, float min, float max);
```

This example assumes A0 is configured for 0~5V input and A2 for 0(4)~20mA input. Both functions scale the ADC input to the specified min~max range. IanalogRead() returns an integer with the fractional part discarded; IanalogReadf() returns a floating-point value. This example displays the 0~5V input on A0 as both 0~100% and voltage. For the 0~20mA input on A2, specify a range of 0~20 to read the actual current.

```cpp
void setup() {
  Serial.begin(115200);
}
 
void loop() {
  const int32_t percent = IanalogRead(A0, 0, 100);  // Scale A0 to an integer from 0~100%
  const float voltage = IanalogReadf(A0, 0.0f, 5.0f);  // Scale A0 to a floating-point voltage from 0~5V
  const float current = IanalogReadf(A2, 0.0f, 20.0f);  // Scale A2 to a floating-point current from 0~20mA
  Serial.print(F("A0: "));
  Serial.print(percent);
  Serial.print(F(" %, "));
  Serial.print(voltage, 2);
  Serial.print(F(" V, A2: "));
  Serial.print(current, 2);
  Serial.println(F(" mA"));
  delay(500);
}
```

#### Function example · 4~20mA range scaling: IanalogRead2(), IanalogRead2f()

**Function prototype**

```cpp
int32_t IanalogRead2(uint8_t ch, int32_t min, int32_t max);
float IanalogRead2f(uint8_t ch, float min, float max);
```

This example assumes A0 is configured for 0~5V input and A2 for 0(4)~20mA input. Scale a 4~20mA sensor input connected to A2 to a user-defined range. IanalogRead2(A2, 0, 100) returns an integer with 4mA mapped to 0% and 20mA to 100%. IanalogRead2f(A2, 4.0f, 20.0f) returns the current as a floating-point value. Below approximately 3.6mA, both functions return ANALOG\_READ2\_ERROR(65535); from approximately 3.6~4mA, they return the specified minimum.

```cpp
void setup() {
  Serial.begin(115200);
}
 
void loop() {
  const int32_t percent = IanalogRead2(A2, 0, 100);  // Scale A2 4~20mA to an integer from 0~100%
  const float current = IanalogRead2f(A2, 4.0f, 20.0f);  // Convert A2 4~20mA to a floating-point current
  if (percent == ANALOG_READ2_ERROR ||
      current == (float)ANALOG_READ2_ERROR) {
    Serial.println(F("A2: 4-20mA input error"));
  } else {
    Serial.print(F("A2: "));
    Serial.print(percent);
    Serial.print(F(" %, "));
    Serial.print(current, 2);
    Serial.println(F(" mA"));
  }
  delay(500);
}
```

#### Function example · moving average: analogReadAvg(), analogRead2Avg()

**Function prototype**

```cpp
int32_t analogReadAvg(uint8_t ch, uint8_t samples);
int32_t analogRead2Avg(uint8_t ch, uint8_t samples);
```

This example assumes A0 is configured for 0~5V input and A2 for 0(4)~20mA input. analogReadAvg(A0, 5) returns a moving average of the raw A0 ADC readings (0~1023). analogRead2Avg(A2, 5) averages the corrected A2 4~20mA values (4mA=0, 20mA=32767). Each function accumulates up to 5 valid readings from recent calls; it does not take 5 readings in one call. The maximum samples value is 20. analogRead2Avg() returns ANALOG\_READ2\_AVG\_ERROR(-1) for inputs below approximately 3.6mA.

```cpp
void setup() {
  Serial.begin(115200);
}
 
void loop() {
  const int32_t voltageAvg = analogReadAvg(A0, 5);  // Moving average of up to 5 recent A0 ADC values
  const int32_t currentAvg = analogRead2Avg(A2, 5);  // Moving average of up to 5 recent corrected A2 4~20mA values
  Serial.print(F("A0 ADC average: "));
  Serial.print(voltageAvg);
  Serial.print(F(", A2 4-20mA average: "));
  if (currentAvg == ANALOG_READ2_AVG_ERROR) {
    Serial.println(F("input error"));
  } else {
    Serial.println(currentAvg);
  }
  delay(500);
}
```

### Example program · temperature sensor inputs

Use analogRead() to display the temperature-sensor ADC raw values (0~1023) of A4, A5. Celsius conversion is explained in the built-in functions below.

```cpp
void setup() {
  Serial.begin(115200);
}
 
void loop() {
  Serial.print(F("A4 ADC: "));
  Serial.println(analogRead(A4));
  Serial.print(F("A5 ADC: "));
  Serial.println(analogRead(A5));
  delay(500);
}
```

**Related built-in functions**

#### Function example · read NTC temperature: ntcRead(), ntcReadf()

**Function prototype**

```cpp
int ntcRead(uint8_t ch);
float ntcReadf(uint8_t ch);
```

Read the temperature of the NTC 10kΩ (25℃), B=3950K sensor connected to NTC input A4. ntcRead() returns an integer equal to 10 times the Celsius temperature (25.3℃ → 253); ntcReadf() returns the Celsius temperature as a floating-point value (25.3). Both have a resolution of 0.1℃. Values outside the conversion range are clamped to -40℃ or 120℃, so do not use these values to detect an open or short circuit.

```cpp
void setup() {
  Serial.begin(115200);
}
 
void loop() {
  const int temperature10 = ntcRead(A4);  // Return A4 temperature as an integer in Celsius ×10
  const float temperature = ntcReadf(A4);  // Return A4 temperature as floating-point Celsius
  Serial.print(F("ntcRead: "));
  Serial.print(temperature10);
  Serial.print(F(" (0.1 C), ntcReadf: "));
  Serial.print(temperature, 1);
  Serial.println(F(" C"));
  delay(500);
}
```

## PWM and High-Speed Inputs

| Function | Arduino Pin | Points | Connector Pinout |
| --- | --- | --- | --- |
| PWM outputs | D21, D22, D23, D26, D27, D28 | 6 points | [MPINO-8A4R-SU PWM output connector pinout](https://www.ilogics.net/docs/_media/en-us_products:mpino-8a4r-su-pwm-output.svg "en-us_products:mpino-8a4r-su-pwm-output.svg") |
| High-Speed Inputs / Interrupts | D18, D19, D24, D25 | 4 points |
| Encoder Inputs | D24, D25 | 2 points |

D18 and D19 share the I²C SCL·SDA functions; D24 and D25 share the FND/ENCO CLK·DIO functions. The two functions of the same pin cannot be used simultaneously.

### Example program · PWM outputs

Set analogWrite() duty value 128 in the 0~255 range on D21, D22, D23, D26, D27, D28 to output approximately 50% PWM.

```cpp
void setup() {
  analogWrite(21, 128);
  analogWrite(22, 128);
  analogWrite(23, 128);
  analogWrite(26, 128);
  analogWrite(27, 128);
  analogWrite(28, 128);
}
 
void loop() {
}
```

**Related built-in functions**

#### Function example · specify duty value: PWM()

**Function prototype**

```cpp
void PWM(uint8_t pin, uint16_t val, bool onDutybit16 = false);
```

PWM(pin, val, onDutybit16) sets the duty value. The 8-bit range is 0~255; with the third argument true, the 16-bit range is 0~65535. Output the 16-bit midpoint value 32768 on D21. D21~D23 share Timer3, and D26~D28 share Timer1; use the same resolution on the same timer. Start after calling PWM\_RESET().

```cpp
void setup() {
  PWM_RESET();  // Stop PWM timers and reset their modes
  PWM(21, 32768, true);  // Output a midrange 16-bit duty value on D21
}
 
void loop() {
}
```

#### Function example · set frequency/duty: FDPWM()

**Function prototype**

```cpp
void FDPWM(uint8_t pin, int32_t intHz, float Duty);
```

FDPWM(pin, intHz, Duty) specifies the frequency (Hz) and duty cycle (%). Output 1kHz at 50% duty on D21. D21~D23 share Timer3, and D26~D28 share Timer1; specify the same frequency for outputs on the same timer. There is no separate FPWM() function; use FDPWM(pin, hz, 50.0f) for 50% duty output.

```cpp
void setup() {
  PWM_RESET();  // Stop PWM timers and reset their modes
  FDPWM(21, 1000, 50.0f);  // Output 1kHz at 50% duty on D21
}
 
void loop() {
}
```

#### Function example · output a specified pulse count: NPWM\_BEGIN(), NPWM()

**Function prototype**

```cpp
void NPWM_BEGIN(uint8_t pin, uint32_t intHz, float Duty, uint32_t N);
void NPWM(uint8_t pin);
```

Use NPWM\_BEGIN() to prepare 100 pulses at 1kHz and 50% duty on D21, then run NPWM() on every loop() iteration to handle output and completion. Do not insert delay(). D21~D23 share Timer3, and D26~D28 share Timer1; do not combine this with other outputs on the same timer.

```cpp
void setup() {
  PWM_RESET();  // Stop PWM timers and reset their modes
  NPWM_BEGIN(21, 1000, 50.0f, 100);  // Prepare 100 pulses at 1kHz, 50% duty on D21
}
 
void loop() {
  NPWM(21);  // Process the prepared pulse output and completion
}
```

#### Function example · stop/resume channel output: PWMOFF()

**Function prototype**

```cpp
void PWMOFF(uint8_t pin, bool POff);
```

PWMOFF(pin, true) sets the channel stop flag; false clears it. Call FDPWM() immediately after setting the flag to apply it to the output connection. Turn D21 on for 2 seconds and off for 2 seconds; after stopping, hold LOW with digitalWrite(). This stop flag does not apply to NPWM().

```cpp
void setup() {
  PWM_RESET();  // Stop PWM timers and reset their modes
}
 
void loop() {
  PWMOFF(21, false);  // Clear the stop state of D21
  FDPWM(21, 1000, 50.0f);  // Apply the cleared flag and start 1kHz, 50% output
  delay(2000);
 
  PWMOFF(21, true);  // Set the stop state of D21
  FDPWM(21, 1000, 50.0f);  // Apply the stop flag and disconnect PWM output
  digitalWrite(21, LOW);
  delay(2000);
}
```

#### Function example · stop/reset PWM timers: PWM\_RESET()

**Function prototype**

```cpp
void PWM_RESET();
```

PWM\_RESET() resets the Timer1·Timer3 control registers and counters. Output 1kHz on D21 for 2 seconds, then stop all timers. This also affects PWM and counters on the same timer. It does not also clear the PWMOFF() stop flag.

```cpp
void setup() {
  PWM_RESET();  // Stop PWM timers and reset their modes
  FDPWM(21, 1000, 50.0f);  // Output 1kHz at 50% duty on D21
  delay(2000);
  PWM_RESET();  // Stop and reset all Timer1/Timer3 PWM outputs
  digitalWrite(21, LOW);
}
 
void loop() {
}
```

### Example program · pulse counting

Count FALLING edges on CLK(D24). The input has a 10kΩ pull-up. This software interrupt example reads the 32-bit value with ATOMIC\_BLOCK and displays it every 500ms. Lossless counting is not guaranteed at the maximum input frequency.

```cpp
static_assert(digitalPinToInterrupt(CLK) != NOT_AN_INTERRUPT, "Invalid interrupt input");
 
#include <util/atomic.h>
 
volatile uint32_t pulseCount = 0;
 
void countPulse() {
  pulseCount++;
}
 
void setup() {
  Serial.begin(115200);
  // Count at the selected edge of the input signal
  attachInterrupt(digitalPinToInterrupt(CLK), countPulse, FALLING);
}
 
void loop() {
  uint32_t snapshot;
  ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
    snapshot = pulseCount;
  }
  Serial.print(F("CLK pulses: "));
  Serial.println(snapshot);
  delay(500);
}
```

### Example program · encoder inputs

Connect phase A to CLK(D24) and phase B to DIO(D25). This x1 counting example uses a 10kΩ pull-up and increments when phase B is LOW at a FALLING edge. The actual rotation direction depends on the phase A/B wiring.

```cpp
static_assert(digitalPinToInterrupt(CLK) != NOT_AN_INTERRUPT, "Invalid interrupt input");
 
#include <util/atomic.h>
#include <stdint.h>
 
volatile int32_t position = 0;
 
void readEncoder() {
  // Increment if phase B is LOW at the phase A falling edge (x1 decoding)
  if (digitalRead(DIO) == LOW) {
    if (position < INT32_MAX) position++;
  } else {
    if (position > INT32_MIN) position--;
  }
}
 
void setup() {
  Serial.begin(115200);
  // Encoder phase A → CLK(D24), phase B → DIO(D25)
  attachInterrupt(digitalPinToInterrupt(CLK), readEncoder, FALLING);
}
 
void loop() {
  int32_t snapshot;
  ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
    snapshot = position;
  }
  Serial.print(F("Encoder: "));
  Serial.println(snapshot);
  delay(500);
}
```

## Communication and Upload

| Function | Arduino Pin | Object | Device Wiring |
| --- | --- | --- | --- |
| USB Upload / Monitoring | D16(RX0), D17(TX0) | `Serial` | [MPINO-8A4R-SU communication connectors and device wiring](https://www.ilogics.net/docs/_media/en-us_products:mpino-8a4r-su-communication.svg "en-us_products:mpino-8a4r-su-communication.svg") |
| RS-485 | Serial1 dedicated pins | `Serial1` |
| I²C | D18(SCL), D19(SDA) | `Wire` |
| SPI | D8(SS), D9(SCK), D10(MOSI), D11(MISO) | `SPI` |

RS-485 includes an automatic direction-control circuit, so no separate transmit/receive direction pin is needed.

### Example program · basic communication

Forward characters between Serial(115200bps) and RS-485 Serial1(9600bps, 8-N-1). Check the free space in the transmit buffer with availableForWrite(). RS-485 uses automatic direction control; no separate direction pin is configured.

```cpp
// Serial Monitor via MP download cable ↔ RS-485 Serial1
void setup() {
  Serial.begin(115200);
  Serial1.begin(9600);  // Also configure the other device for 9600 bps, 8-N-1
}
 
void loop() {
  if (Serial.available() && Serial1.availableForWrite()) {
    Serial1.write(Serial.read());
  }
  if (Serial1.available() && Serial.availableForWrite()) {
    Serial.write(Serial1.read());
  }
}
```

### Example program · I²C communication

Use Wire to scan addresses 0x08~0x77 and display responding addresses every 3 seconds. Do not run this simultaneously with encoder/interrupt examples that use SDA·SCL.

```cpp
#include <Wire.h>
 
void setup() {
  Serial.begin(115200);
  Wire.begin();
  Wire.setClock(100000);
}
 
void loop() {
  uint8_t found = 0;
  for (uint8_t address = 0x08; address <= 0x77; address++) {
    Wire.beginTransmission(address);
    const uint8_t result = Wire.endTransmission();
    if (result == 0) {
      Serial.print(F("I2C: 0x"));
      if (address < 16) Serial.print('0');
      Serial.println(address, HEX);
      found++;
    }
  }
  Serial.print(F("Devices: "));
  Serial.println(found);
  delay(3000);
}
```

### Example program · Modbus RTU communication

**Related built-in functions**

#### Function example · Modbus RTU Slave: ImodbusRTUMem(), ImodbusRTUAdr(), ImodbusRTUInit(), ImodbusRTU()

**Function prototype**

```cpp
void ImodbusRTUMem(uint16_t m_size, uint16_t d_size);
void ImodbusRTUAdr(uint16_t m_offset, uint16_t d_offset);
void ImodbusRTUInit(HardwareSerial& serialPort, uint8_t slaveId, long baudrate);
void ImodbusRTU();
```

Store the D0 state in M[0] and the A0 raw value (0~1023) in D[0] for the other device to read. Configure RS-485(Serial1), station 1, 9600bps, 8N1. Read M[0] with FC01, start address 0, 1 bit; read D[0] with FC03, start address 0, 1 word. Addresses are actual transmitted addresses, starting from 0. Call the communication function on every loop() iteration; this example does not control outputs.

M and D are shared global memory provided by the core. Run this sketch on its own. When combining protocols, do not allocate the shared memory more than once.

```cpp
unsigned long lastPrint = 0;
bool memoryReady = false;
 
void setup() {
  Serial.begin(115200);
  ImodbusRTUMem(8, 8);  // Allocate 8 M bits and 8 D words
  ImodbusRTUAdr(0, 0);  // Set the M and D communication start addresses to 0
  ImodbusRTUInit(Serial1, 1, 9600);  // Start RS-485 at station 1, 9600bps
  memoryReady = (M != nullptr && D != nullptr);
  if (!memoryReady) Serial.println(F("Memory allocation failed"));
}
 
void loop() {
  if (!memoryReady) return;
  M[0] = digitalRead(0);
  D[0] = analogRead(A0);
  ImodbusRTU();  // Process incoming Modbus RTU requests
 
  if (millis() - lastPrint >= 1000) {
    lastPrint = millis();
    Serial.print(F("M[0]: "));
    Serial.print(M[0]);
    Serial.print(F(", D[0]: "));
    Serial.println(D[0]);
  }
}
```

#### Function example · Modbus RTU Master: ImodbusRTUmasterInit(), ImodbusRTUmaster()

**Function prototype**

```cpp
void ImodbusRTUmasterInit(HardwareSerial& serialPort, long baudrate, uint8_t config);
uint8_t ImodbusRTUmaster(HardwareSerial& serialPort, uint8_t slaveId, uint8_t functionCode, uint16_t address, uint16_t quantity, uint16_t* data, uint16_t timeoutMs = 100);
```

Read 1 holding register from the slave every 1 second over RS-485(Serial1). Configure the other device for station 1, 9600bps, 8N1, FC03, and on-wire start address 0. The response is stored in received[0] and displayed only on success. Error codes are displayed in hexadecimal. This is a separate sketch from the slave example above and uses a receive array instead of M/D memory.

```cpp
unsigned long lastRequest = 0;
uint16_t received[1];
 
void setup() {
  Serial.begin(115200);
  ImodbusRTUmasterInit(Serial1, 9600, SERIAL_8N1);  // Start RS-485 as a Modbus master
}
 
void loop() {
  if (millis() - lastRequest < 1000) return;
  lastRequest = millis();
  const uint8_t result = ImodbusRTUmaster(Serial1, 1, 3, 0, 1, received, 200);  // Read 1 word at address 0 from station 1, timeout 200ms
 
  if (result == IMODBUS_RTU_SUCCESS) {
    Serial.print(F("Register 0: "));
    Serial.println(received[0]);
  } else {
    Serial.print(F("Modbus error: 0x"));
    Serial.println(result, HEX);
  }
}
```

### Example program · LS Industrial Systems Cnet communication

**Related built-in functions**

#### Function example · LS Industrial Systems Cnet SLave: ICnetMem(), ICnetAdr(), ICnetInit(), ICnet()

**Function prototype**

```cpp
void ICnetMem(uint16_t m_size, uint16_t d_size, uint16_t r_size = 100);
void ICnetAdr(uint16_t m_offset, uint16_t d_offset, uint16_t r_offset = 0);
void ICnetInit(HardwareSerial& serialPort, uint8_t slaveId, long baudrate);
void ICnet();
```

Store the D0 state in M[0] and the A0 raw value (0~1023) in D[0] for the HMI to read. Configure the other device for LS Industrial Systems Cnet, RS-485, station 1, 9600bps, 8N1. Read %MX00000(M[0]) for the bit and %DW0(D[0]) for the word. Call the communication function on every loop() iteration; this example does not control outputs.

M, D, and R are shared global memory provided by the core; this example does not use R. Run this separately from the Modbus example. When combining protocols, do not allocate the shared memory more than once.

```cpp
unsigned long lastPrint = 0;
bool memoryReady = false;
 
void setup() {
  Serial.begin(115200);
  ICnetMem(8, 8, 0);  // Allocate 8 M bits and 8 D words; R is unused
  ICnetAdr(0, 0, 0);  // Set the M and D communication start addresses to 0
  ICnetInit(Serial1, 1, 9600);  // Start RS-485 at station 1, 9600bps
  memoryReady = (M != nullptr && D != nullptr);
  if (!memoryReady) Serial.println(F("Memory allocation failed"));
}
 
void loop() {
  if (!memoryReady) return;
  M[0] = digitalRead(0);
  D[0] = analogRead(A0);
  ICnet();  // Process incoming LS Cnet requests
 
  if (millis() - lastPrint >= 1000) {
    lastPrint = millis();
    Serial.print(F("M[0]: "));
    Serial.print(M[0]);
    Serial.print(F(", D[0]: "));
    Serial.println(D[0]);
  }
}
```

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