Sporadic timeout error in serial communication ruins program. How do I ignore it and retry?

Hello,

So the problem that I'm having is when writing values to an external device using a serial port. The serial port is set up as follows:

    handles.s = serial('COM1');
    handles.s.BaudRate = 115200;
    handles.s.DataBits = 8;
    handles.s.StopBits = 1;
    handles.s.Parity = 'NONE';
    handles.s.InputBufferSize = (1024*100);
    handles.s.Timeout = 3;
    fopen(handles.s);

And this code works most of the time. I output values in a loop that uses the function show below to grab them from a GUI and output through the serial port:

    function setValue(i, num, hObject, handles, negative)

    string = strcat('Setting values (',num2str(i),')');
    set(handles.status,'String',string);
    fwrite(handles.s,255);
    fwrite(handles.s,num);
    if(negative == 0)
        fwrite(handles.s,floor(str2double(get(hObject,'String'))/256));
        fwrite(handles.s,mod(str2double(get(hObject,'String')),256));
    else
        fwrite(handles.s,floor(-str2double(get(hObject,'String'))/256));
        fwrite(handles.s,mod(-str2double(get(hObject,'String')),256));    
    end
    pause(.01);

The problem is that sometimes, unpredictably, the values will stop writing because of a timeout error. This requires me to shut down matlab and my hardware components, restart the machinery, and then reconnect matlab. If matlab could just try writing the value again, I could program my hardware components to ignore bad data and accept the new values... but matlab refuses to work after there has been a timeout error unless it is restarted.

I have read while searching for a solution that there may be "handshake pins" that need to be provided a steady voltage for serial communication to work properly... perhaps this is the solution? If so, where are these magical pins?

Thanks,

Erich

Answer 1

[Erich Glück]

Turns out I was just writing values too quickly which due to internal shenanigans sporadically overflowed the output buffer resulting in a timeout. This was fixed by replacing the pause(.01) with pause(.1).. slower transmit of data but at least it's reliable.

Erich

[Akshay Datar]

Thanks Erich, I had same problem of timeout error and needed to restart matlab everytime. But by setting pause(0.1),problem is solved.