C# Serial Communications issues with Arduino

Question

I have been struggling with commincations speeds with some code.

So i want to increase the baud rate for both the code & Arduino. But if i leave the 9600 baud rate, the data stops sending & reciving properly. So i set up a simple test program.

Arduino Code:

void setup()
{
    Serial.begin(9600);
    Serial.setTimeout(10);
}

void loop()
{
    if (Serial.available())
    {
        String Data = Serial.readStringUntil('#');
        if (Data == "Test")
        {
            Serial.println("Recived");
        }
    }
    delay(1);
}

c# Code:

SerialPort Port = new SerialPort("COM4", 9600);
Port.Open();
if (Port.IsOpen)
{
     Port.Write("Test#");
     System.Threading.Thread.Sleep(1000);
     String Read = Port.ReadExisting();
     Port.Close();
}

So running that String Read comes back with "Recived\r\n". Change the baud rate to 19200 and it comes back with "".

Any ideas why this is occuring?

Edit: If I use the Arduino IDE's Serial Monitor Program, this works just fine regardless of baudrate used. Its as soon as i use c# that it that this issue occurs. Which rules out hardware issues I believe.

Answer 1

Thankyou for you inputs.

Think i have found a solution, although not to clear about why.

I think it was due to the Serial.Avalible() Command. Appears i needed to send though some data first to make it register the port is open.

So modifying my C# code to this: Works

SerialPort Port = new SerialPort("COM4", 9600);
Port.Open();
if (Port.IsOpen)
{
     Port.Write("#");
     Port.Write("Test#");
     System.Threading.Thread.Sleep(1000);
     String Read = Port.ReadExisting();
     Port.Close();
}

Thanks a lot