Not Receiving Data in SerialPortReader Stream

[Rockstar95]

On MCP23017 Board, Not Getting Serial Data.

After Running The Below Code, Port is Opened to read Successfuly, but not getting any data into stream

SerialPort myPort = SerialPort("COM8");

bool isOpen = myPort.openRead();
print("isOpen:${isOpen}"); //isOpen:true

SerialPortReader mySerialPortReader = SerialPortReader(myPort, timeout: 500);

mySerialPortReader.stream.listen(
(Uint8List data) {
print("Data in Stream:${data}");
dataList.add(data);
},
cancelOnError: true,
onDone: () {
print("MySerialPort Stream Done");
},
);