CentralizedControl/NModbus/Device/ModbusSerialMaster.cs

using System.Diagnostics.CodeAnalysis;
using NModbus.Data;
using NModbus.Message;

namespace NModbus.Device
{
    /// <summary>
    ///     Modbus serial master device.
    /// </summary>
    public class ModbusSerialMaster : ModbusMaster, IModbusSerialMaster
    {
        public ModbusSerialMaster(IModbusSerialTransport transport)
            : base(transport)
        {
        }

        /// <summary>
        ///     Gets the Modbus Transport.
        /// </summary>
        [SuppressMessage("Microsoft.Design", "CA1033:InterfaceMethodsShouldBeCallableByChildTypes")]
        IModbusSerialTransport IModbusSerialMaster.Transport => (IModbusSerialTransport)Transport;

        /// <summary>
        ///     Serial Line only.
        ///     Diagnostic function which loops back the original data.
        ///     NModbus only supports looping back one ushort value, this is a limitation of the "Best Effort" implementation of
        ///     the RTU protocol.
        /// </summary>
        /// <param name="slaveAddress">Address of device to test.</param>
        /// <param name="data">Data to return.</param>
        /// <returns>Return true if slave device echoed data.</returns>
        public bool ReturnQueryData(byte slaveAddress, ushort data)
        {
            DiagnosticsRequestResponse request = new DiagnosticsRequestResponse(
                ModbusFunctionCodes.DiagnosticsReturnQueryData,
                slaveAddress,
                new RegisterCollection(data));

            DiagnosticsRequestResponse response = Transport.UnicastMessage<DiagnosticsRequestResponse>(request);

            return response.Data[0] == data;
        }
    }
}