arduinomodbus库例程

以下是一个使用Arduino Modbus库的例程：

#include <ArduinoModbus.h>

// Define modbus slave ID
#define MODBUS_SLAVE_ID 1

// Define modbus function codes
#define MODBUS_READ_HOLDING_REGISTERS 0x03
#define MODBUS_WRITE_SINGLE_REGISTER 0x06

// Define modbus register addresses
#define REG_ADDRESS_LED_STATUS 0x0000

// Define LED pin
#define LED_PIN 13

// Create modbus object
Modbus slave(MODBUS_SLAVE_ID, 0, 0);

void setup() {
  // Initialize LED pin
  pinMode(LED_PIN, OUTPUT);

  // Initialize modbus communication
  slave.begin(19200);
  slave.addHreg(REG_ADDRESS_LED_STATUS);
}

void loop() {
  // Check for modbus request
  if (slave.poll()) {
    // Get function code
    uint8_t func = slave.getFunction();

    // Handle read holding registers request
    if (func == MODBUS_READ_HOLDING_REGISTERS) {
      // Get register address and quantity
      uint16_t addr = slave.getWord();
      uint16_t qty = slave.getWord();

      // Check if the requested register address is valid
      if (addr == REG_ADDRESS_LED_STATUS) {
        // Set the LED status value to the register value
        slave.Hreg(REG_ADDRESS_LED_STATUS, digitalRead(LED_PIN));
      }
    }

    // Handle write single register request
    else if (func == MODBUS_WRITE_SINGLE_REGISTER) {
      // Get register address and value
      uint16_t addr = slave.getWord();
      uint16_t value = slave.getWord();

      // Check if the requested register address is valid
      if (addr == REG_ADDRESS_LED_STATUS) {
        // Set the LED status to the register value
        digitalWrite(LED_PIN, value);
      }
    }
  }
}

此例程将Arduino作为Modbus从站，并将LED状态作为Modbus寄存器的值。从站将处理读取保持寄存器请求和写入单个寄存器请求。当从站收到读取保持寄存器请求时，它将检查请求的寄存器地址是否为LED状态寄存器地址，并将寄存器值设置为LED状态值。当从站收到写单个寄存器请求时，它将检查请求的寄存器地址是否为LED状态寄存器地址，并将LED状态设置为寄存器值。