/// <summary>
/// Modbus serial ASCII master and slave example.
/// </summary>
public static void ModbusSerialAsciiMasterReadRegistersFromModbusSlave()
{
using (SerialPort masterPort = new SerialPort("COM1"))
using (SerialPort slavePort = new SerialPort("COM2"))
{
// configure serial ports
masterPort.BaudRate = slavePort.BaudRate = 9600;
masterPort.DataBits = slavePort.DataBits = 8;
masterPort.Parity = slavePort.Parity = Parity.None;
masterPort.StopBits = slavePort.StopBits = StopBits.One;
masterPort.Open();
slavePort.Open();
var slaveAdapter = new SerialPortAdapter(slavePort);
// create modbus slave on seperate thread
byte slaveId = 1;
var factory = new ModbusFactory();
var transport = factory.CreateAsciiTransport(slaveAdapter);
var network = factory.CreateSlaveNetwork(transport);
var slave = factory.CreateSlave(slaveId);
network.AddSlave(slave);
var listenTask = network.ListenAsync();
var masterAdapter = new SerialPortAdapter(masterPort);
var masterTransport = factory.CreateAsciiTransport(masterAdapter);
// create modbus master
IModbusSerialMaster master = factory.CreateMaster(masterTransport);
master.Transport.Retries = 5;
ushort startAddress = 100;
ushort numRegisters = 5;
// read five register values
ushort[] registers = master.ReadHoldingRegisters(slaveId, startAddress, numRegisters);
for (int i = 0; i < numRegisters; i++)
{
Console.WriteLine($"Register {(startAddress + i)}={registers[i]}");
}
}
// output
// Register 100=0
// Register 101=0
// Register 102=0
// Register 103=0
// Register 104=0
}