arduino测试ArduinoModbus库例程

测试硬件：arduino nano
arduino mega2560 pro
Arduino版本1.8.13
ArduinoModbus库版本：1.0.3
首先安装ArduinoModbus库

还有一个依赖库

例程

/*
  Modbus RTU Server Kitchen Sink

  This sketch creates a Modbus RTU Server and demonstrates
  how to use various Modbus Server APIs.

  Circuit:
   - MKR board
   - MKR 485 shield
     - ISO GND connected to GND of the Modbus RTU server
     - Y connected to A/Y of the Modbus RTU client
     - Z connected to B/Z of the Modbus RTU client
     - Jumper positions
       - FULL set to OFF
       - Z \/\/ Y set to OFF

  created 18 July 2018
  by Sandeep Mistry
*/

#include <ArduinoRS485.h> // ArduinoModbus depends on the ArduinoRS485 library
#include <ArduinoModbus.h>

const int numCoils = 10;
const int numDiscreteInputs = 10;
const int numHoldingRegisters = 10;
const int numInputRegisters = 10;

void setup() {
    
    
  Serial.begin(9600);
  while (!Serial);

  Serial.println("Modbus RTU Server Kitchen Sink");

  // start the Modbus RTU server, with (slave) id 42
  if (!ModbusRTUServer.begin(42, 9600)) {
    
    
    Serial.println("Failed to start Modbus RTU Server!");
    while (1);
  }

  // configure coils at address 0x00
  ModbusRTUServer.configureCoils(0x00, numCoils);

  // configure discrete inputs at address 0x00
  ModbusRTUServer.configureDiscreteInputs(0x00, numDiscreteInputs);

  // configure holding registers at address 0x00
  ModbusRTUServer.configureHoldingRegisters(0x00, numHoldingRegisters);

  // configure input registers at address 0x00
  ModbusRTUServer.configureInputRegisters(0x00, numInputRegisters);
}

void loop() {
    
    
  // poll for Modbus RTU requests
  ModbusRTUServer.poll();

  // map the coil values to the discrete input values
  for (int i = 0; i < numCoils; i++) {
    
    
    int coilValue = ModbusRTUServer.coilRead(i);

    ModbusRTUServer.discreteInputWrite(i, coilValue);
  }

  // map the holding register values to the input register values
  for (int i = 0; i < numHoldingRegisters; i++) {
    
    
    long holdingRegisterValue = ModbusRTUServer.holdingRegisterRead(i);

    ModbusRTUServer.inputRegisterWrite(i, holdingRegisterValue);
  }
}

nano编译后内存占用大致50%
mega2560 pro编译后5%
注意要配合TTL转485进行测试（直接usb串口测试不成功）
必须使用硬件串口Serial