arduinomodbus库例程

以下是使用Arduino Modbus库的简单例程：

#include <ModbusMaster.h>

// ModbusMaster object
ModbusMaster node;

void setup() {
  Serial.begin(9600); // start serial communication
  node.begin(1, Serial); // set the Modbus slave ID to 1, and use Serial for communication
}

void loop() {
  uint8_t result;
  uint16_t data; // variable to hold the received data

  // read a holding register (address 0x0000) from Modbus master with ID 2
  result = node.readHoldingRegisters(0x0000, 1, 2);

  // check if the read was successful
  if (result == node.ku8MBSuccess) {
    data = node.getResponseBuffer(0);
    Serial.println(data); // print the received data
  } else {
    Serial.println("Read failed"); // print an error message
  }

  delay(500); // wait for 500 milliseconds before reading again
}

此示例从Modbus主站读取保持寄存器0x0000的值，并将其打印到串行监视器上。在每次循环中等待500毫秒后，它将再次读取该值。请注意，此示例假定有一个Modbus主站，其ID设置为2，并且已正确配置Modbus从站（Arduino）的Modbus地址。