public override void Run(TaskContext context)
        {
            var serialPort1 = new SerialPort("COM3", 9600, Parity.None, 8, StopBits.One);
            try
            {
                context.WriteLog($"開始執行");
                serialPort1.ReadTimeout = 10 * 1000;
                serialPort1.Open();

                IModbusSerialMaster master 
 
= ModbusSerialMaster.CreateRtu(serialPort1);
                byte slaveId = 1;//當前裝置的地址為1
                var returnData = master.ReadHoldingRegisters(slaveId, 0, 2);


                var temoperatureValue = returnData[0] / (double)10;
                var humidityValue = returnData[1] / (double)10;

                context.WriteLog($
 
"value:" + temoperatureValue + "|" + humidityValue);
            }
            catch (Exception ex)
            {
                context.WriteLog($"er:" + ex.Message + "|" + ex.StackTrace);
            }
            finally
            {
                serialPort1.Close();
            }
            context.WriteLog($
 
"當前時是：{DateTime.Now}");
        }
    }

serialPort1.ReadTimeout = 10 * 1000;
如果不設定這個超時，就會一直等待，影響後面的執行。