Modbus readholdingregisters - tcpclient

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Я получаю следующее сообщение об ошибке при ReadingHoldingRegisters с использованием протокола Modbus

Unable to read data from the transport connection: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.

Что я уже пробовал:

string ipAddress = "10.100.10.80";
int tcpPort = 30000;
TcpClient tcpClient = new TcpClient(); // Create a new TcpClient object.                tcpClient.Connect(ipAddress, tcpPort);


ModbusIpMaster modmaster = ModbusIpMaster.CreateIp(tcpClient);
modmaster.Transport.ReadTimeout = 5000;
modmaster.Transport.WriteTimeout = 5000;



byte slaveID = 1;
 ushort sstartAddress = 1;
 ushort numOfPoints = 10;
 ushort[] holding_register = modmaster.ReadHoldingRegisters(slaveID, sstartAddress, numOfPoints);

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