# 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.

## 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-232 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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