why is access to com port denied?

Question

the code:

static void Main(string[] args)
{
    Console.WriteLine(\"Memory mapped file reader started\");

    using (var file = MemoryMappedFile.OpenExistin         


        

Answer 1

In addition to Hans' answer:

I had the same problem and played around a bit with some sleep times between opening and closing the serial port. In my case 250 ms were sufficient. Maybe this will help out somebody out there.

EDIT:

I optimized my solution and this is what I came up with:

int maxRetries = 20;
const int sleepTimeInMs = 50;
string loggingMessage = string.Empty;

while (maxRetries > 0)
{
    try
    {
        loggingMessage = "Opening serial port '" + mSerialPort.PortName + "'...";
        mSerialPort.Open();
        loggingMessage += "Succeeded.";
        IOLogger.LogInfo(loggingMessage);
    }
    catch (UnauthorizedAccessException unauthorizedAccessException)
    {
        maxRetries--;
        loggingMessage += "Failed (UnauthorizedAccessException): ";
        IOLogger.LogError(string.Format(loggingMessage + unauthorizedAccessException.Message + " -> Retrying in about {0} milliseconds...", sleepTimeInMs));
        Thread.Sleep(sleepTimeInMs);
    }
    catch (Exception exception)
    {
        loggingMessage += "Failed: ";
        IOLogger.LogError(loggingMessage + exception.Message);
    }
}

You can play around with the sleepTimeInMs and/or the maxRetries. I have chosen those values because they seemed to be sufficient in any needed use case.