C/C++ • SoftwareSerial & SerialPIO on Pico 2W

Code:

/*  *  TempHumidRS485_3.ino *  Robin Greig *  2025.02.17 *   *  Reads the Temp & Humidity of RS485 device and prints it to Serial Monitor *   *  Using both UARTS and PIO-based UART to read 3 RS485 > TTL inputs *  mySerial1 = Rx / Pin 2 / GPIO 1 & Tx / Pin 1 / GPIO 0 *  mySerial2 = Rx / Pin 7 / GPIO 5 & Tx / Pin 6 / GPIO 4 *  mySerial3 = SerialPIO = Tx / Pin 11 / GPIO 8 & Rx / Pin 12 / GPIO 9 *   *  Based on the ModbusMaster example below*/#include <ModbusMaster.h>       //https://github.com/4-20ma/ModbusMaster#include <SoftwareSerial.h> // Create a SoftwareSerial object to communicate with the MAX485 moduleSoftwareSerial mySerial1(1, 0); // Rx / Pin 2 / GPIO 1 & Tx / Pin 1 / GPIO 0SoftwareSerial mySerial2(5, 4); // Rx / Pin 2 / GPIO 1 & Tx / Pin 1 / GPIO 0SerialPIO mySerial3(8, 9); // Tx / GPIO 8 / Pin 11 & Rx / GPIO 12 / Pin 10//for SoftwareSerial PIO-based UART// Create a ModbusMaster objectModbusMaster node1;ModbusMaster node2;ModbusMaster node3;float humidity1;float humidity2;float humidity3;float temperature1;float temperature2;float temperature3; void setup() {  // Initialize serial communication for debugging  Serial.begin(115200);  // Initialize SoftwareSerial for Modbus communication  mySerial1.begin(9600);  mySerial2.begin(9600);  mySerial3.begin(9600);   // Initialize Modbus communication with the Modbus slave ID 1  node1.begin(1, mySerial1);  node2.begin(1, mySerial2);  node3.begin(1, mySerial3);   // Allow some time for initialization  delay(1000);} void loop() {  uint8_t result1;   // Variable to store the result of Modbus operations  uint16_t data1[2]; // Array to store the data read from the Modbus slave  uint8_t result2;   // Variable to store the result of Modbus operations  uint16_t data2[2]; // Array to store the data read from the Modbus slave  uint8_t result3;   // Variable to store the result of Modbus operations  uint16_t data3[2]; // Array to store the data read from the Modbus slave   // Read 2 holding registers for node1 starting at address 0x0000  // This function sends a Modbus request to the slave to read the registers  result1 = node1.readHoldingRegisters(0x0000, 2);   // If the read is successful, process the data  if (result1 == node1.ku8MBSuccess) {    // Get the response data from the response buffer    data1[0] = node1.getResponseBuffer(0x00); // Humidity    data1[1] = node1.getResponseBuffer(0x01); // Temperature     // Calculate actual humidity and temperature values    humidity1 = data1[0] / 10.0;      // Humidity is scaled by 10    temperature1 = data1[1] / 10.0;   // Temperature is scaled by 10     // Print the values to the Serial Monitor    Serial.print("Humidity1: ");    Serial.print(humidity1);    Serial.println(" %RH");     Serial.print("Temperature1: ");    Serial.print(temperature1);    Serial.println(" °C");    Serial.println();  } else {    // Print an error message if the read fails    Serial.print("Modbus read failed: ");    Serial.println(result1, HEX); // Print the error code in hexadecimal format    Serial.println();  }  delay(200);  // Read 2 holding registers for node2 starting at address 0x0000  // This function sends a Modbus request to the slave to read the registers  result2 = node2.readHoldingRegisters(0x0000, 2);   // If the read is successful, process the data  if (result2 == node2.ku8MBSuccess) {    // Get the response data from the response buffer    data2[0] = node2.getResponseBuffer(0x00); // Humidity    data2[1] = node2.getResponseBuffer(0x01); // Temperature     // Calculate actual humidity and temperature values    humidity2 = data2[0] / 10.0;      // Humidity is scaled by 10    temperature2 = data2[1] / 10.0;   // Temperature is scaled by 10     // Print the values to the Serial Monitor    Serial.print("Humidity2: ");    Serial.print(humidity2);    Serial.println(" %RH");     Serial.print("Temperature2: ");    Serial.print(temperature2);    Serial.println(" °C");    Serial.println();  } else {    // Print an error message if the read fails    Serial.print("Modbus read failed: ");    Serial.println(result2, HEX); // Print the error code in hexadecimal format    Serial.println();  }  delay(200);  // Read 2 holding registers for node3 starting at address 0x0000  // This function sends a Modbus request to the slave to read the registers  result3 = node3.readHoldingRegisters(0x0000, 2);   // If the read is successful, process the data  if (result3 == node3.ku8MBSuccess) {    // Get the response data from the response buffer    data3[0] = node3.getResponseBuffer(0x00); // Humidity    data3[1] = node3.getResponseBuffer(0x01); // Temperature     // Calculate actual humidity and temperature values    humidity3 = data3[0] / 10.0;      // Humidity is scaled by 10    temperature3 = data3[1] / 10.0;   // Temperature is scaled by 10     // Print the values to the Serial Monitor    Serial.print("Humidity3: ");    Serial.print(humidity3);    Serial.println(" %RH");     Serial.print("Temperature3: ");    Serial.print(temperature3);    Serial.println(" °C");    Serial.println();  } else {    // Print an error message if the read fails    Serial.print("Modbus read failed: ");    Serial.println(result3, HEX); // Print the error code in hexadecimal format    Serial.println();  }   // Wait for 2 seconds before the next read  delay(5000);}