SerialPort // Start character, end character, special end character such as <STX>

Question

Hello,

var port = new SerialPort("COM4");
port.Open();
port.ReadTimeout = 10000; // Set the timeout to 10 seconds

var commandsToSend = new string[] { "AT1", "AT2", "AT3" };

foreach (var command in commandsToSend)
{
	try
	{
		Trace.WriteLine($"Write '{command}' to {port.PortName}");
		port.WriteLine(command);

		Trace.WriteLine("Waiting for response...");

		// This will throw a TimeoutException if no data is received within the timeout
		string response = port.ReadLine();

		Trace.WriteLine($"Got response: {response}")

For understanding no.1

The ReadTimeout only works in combination with ReadLine
Do I understand this correctly?
That would be sufficient for me, as the end criterion is <CR>.
ASCII	13	0D 
If I need the EOT character as an end criterion in the future, would that also work simply?
ASCII	4	04

For understanding no.2

The Readline()
-> Manages this when the answer arrives in pieces. So in two or three packages
How would this have to be created correctly if the end is a different character?

For understanding no.3

<STX>XXXXXXXXX<GS>YYYYYY><GS>AAAAAA<STX>
Now I receive this, however
Package 1
WWWWWW<STX>XXXXXXX
Package 2
XX<GS>YYYYYY><GS>AAAAA
Pacakge 3
A<STX>

Answer 1

Hi @Markus Freitag ，

The ReadTimeout property in combination with ReadLine() allows you to set a timeout for how long the system should wait for data to be received before throwing an exception. If you receive data in multiple packages or if your message format changes in the future (e.g., using different end characters like EOT), you'll need to adapt your code accordingly.

If your message format changes to include different end characters, such as <EOT>, which is ASCII 4, you would need to modify your code to accommodate this. Instead of relying on ReadLine(), you might read characters one by one until you encounter the <EOT> character or until a timeout occurs.

string response = "";
char EOT = (char)4; // ASCII code for EOT character

try
{
    Trace.WriteLine($"Write '{command}' to {port.PortName}");
    port.WriteLine(command);

    Trace.WriteLine("Waiting for response...");

    // Read characters until EOT or timeout
    StringBuilder sb = new StringBuilder();
    while (true)
    {
        int nextChar = port.ReadChar();
        if (nextChar == -1) // Timeout occurred
        {
            // Handle timeout error
            throw new TimeoutException("Timeout occurred while waiting for response.");
        }
        char c = (char)nextChar;
        if (c == EOT)
        {
            break; // End of message
        }
        sb.Append(c);
    }
    response = sb.ToString();

    Trace.WriteLine($"Got response: {response}");
}
catch (TimeoutException ex)
{
    Trace.WriteLine($"Error: {ex.Message}");
}

Best Regards.

Jiachen Li

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