Visual Studio Code – C# Application gets stuck by a blocked serial connection due to Arduino board having an internal exception after an established COM port connection

There are a few tactics you may use in your C# program to deal with this scenario:

Read/Write Timeouts:

Using read and write timeouts for the serial port is one technique to keep your program from hanging. This allows your application to capture the timeout and deal with the issue if the Arduino doesn’t react within a predetermined amount of time.

_serialPort.ReadTimeout = 500; 
_serialPort.WriteTimeout = 500;

Async Communication:

One way to avoid blocking the main thread is to read and write using asynchronous techniques. You can use Task, for Task.Run in order to execute serial readings.

async Task ReadFromSerialPort()
{
    try
    {
        while (true)
        {
            string data = await Task.Run(() => _serialPort.ReadLine());
        }
    }
    catch (TimeoutException)
    {
       
    }
    catch (Exception ex)
    {
      
    }
}

Exceptions:

To deal with exceptions, enclose your Open method and all ensuing reads or writes in try-catch blocks. In this manner, you can log the error and possibly attempt to reopen the connection in case something goes wrong.

try
{
    _serialPort.Open();
}
catch (UnauthorizedAccessException ex)
{
   
}
catch (IOException ex)
{
    
}

Serial Port State:

You can keep an eye on the serial port’s condition and possibly shut it off if it stops responding. In order to determine whether the port is still responsive, a different thread or job must be executed.

Cancellation Tokens:

Use cancellation tokens if you implement any long-running operations (such as reading from the serial port). This enables you to stop activities in the event of an error or if they take longer than expected.
for example:

private static SerialPortStream _serialPort;

static async Task Main()
{
    _serialPort = new SerialPortStream("COM6", 9600, 8, Parity.None, StopBits.One)
    {
        ReadTimeout = 500,
        WriteTimeout = 500
    };

    try
    {
        _serialPort.Open();
        await ReadFromSerialPort();
    }
    catch (Exception ex)
    {
        Console.WriteLine($"Error: {ex.Message}");
    }
}

static async Task ReadFromSerialPort()
{
    try
    {
        while (true)
        {
            string data = await Task.Run(() => _serialPort.ReadLine());
        }
    }
    catch (TimeoutException)
    {
        
    }
    catch (IOException ex)
    {
       
    }
    catch (Exception ex)
    {
        
    }
}