Serial Frame Error with No Connection

I never noticed this before on my Cobra board , but it may be normal…

If I send data out a UART when the connections of the port are left disconnected I get frame errors on the SerialPort error event. Is this normal? My Domino does not exhibit this behavior.

static SerialPort UART = new SerialPort("COM1", 115200);
byte[] buffer = Encoding.UTF8.GetBytes("String");
// send the bytes on the serial port
UART.Write(buffer, 0, buffer.Length);


You should never leave input pins unconnected.

I appreciate that, but I allow the user to plug a into the Cobra so it is possible for the connection to be left unconnected and data be transmitted. I just thought it strange that I got frame errors in that case. Do you or anyone else see the same behavior with your EMX/Cobra?


What you see is expected and is normal. You can add a pull up resistor to the pin if you do not need it.