Modbus RTU - ReadHoldingRegisters don't read after 10 seconds #183

I have a problem use this library with Modbus RTU.
I would like to read the data cyclically after a certain period of time (30 seconds), I have problems if I put the time interval greater than or equal to 10 seconds while I have no problems if this is less.
In particular I am using the ReadHoldingRegisters and at the second cycle the application gets stuck on the read and I have a substantial increase cpu use. I tried to set all the client properties (ReadTimeout, Retries ...) but the problem persist.
I have not experienced the same problem with Modbus TCP.
Here is a simple example showing the problem.

`
tcpClient = new TcpClient(hostname, port);
modbusClient = ModbusSerialMaster.CreateRtu(tcpClient);
modbusClient.Transport.ReadTimeout = 1000;
modbusClient.Transport.WriteTimeout = 1000;

        while (true)
        {
            ushort[] result = modbusClient.ReadHoldingRegisters(slaveAddress, address, numRegister);
            foreach (var item in result)
            {
                Console.WriteLine(item);
            }
            Thread.Sleep(10000);
        }`