Arduino Mega 2560 - Serial Port 'COM#' Already in Use

Development Tools IDE 1.x
1

After running the loop back test on my Mega 2560, I am unable to open the serial monitor. I am getting the same error as when I attempted to upload a sketch to the board.
"Serial port 'COM4' already is use. Try quitting any programs that may be using it"

I have tried swapping COM ports, un-installing and re-installing drivers, as well as disabling and enabling COM ports. I have swapped the cable I was using to connect from my PC to Mega 2560 in case it was faulty and now I have done the Loop Back Test.

I have searched through numerous forums now and I am failing to resolve this issue. Any one with any suggestions please let me know. If not, is it likely that this may be a faulty board??

2

Good people of House Arduino,

I have recently bought a new Mega 2560 and I am attempting to upload a sketch to it. I have tried many times but always get the same result. "Serial port 'COM4' already is use. Try quitting any programs that may be using it"

I have tried:

  1. Swapping COM ports
  2. Un-installing and re-installing drivers
  3. Disabling and enabling COM ports
  4. Swapped the cable I was using to connect from my PC to Mega 2560 in case it was faulty
    and now I have done the Loop Back Test.
  5. Loop back test - which I could not perform. I could not open the serial monitor and was presented with the same error code
    Serial Port 'Com#' already in use.

I have searched through numerous forums now and I am failing to resolve this issue. Any one with any suggestions please let me know. If not, is it likely that this may be a faulty board??

3

Please do not cross-post. Threads merged.

4

The usual culprit is PDA / mobile phone software.

5

I have previously used uploaded sketches to my Uno using the same laptop and setup. I have also tried from my work computer which shouldn't have any PDA software on it. All the same result - Com# already in use.

Is there a chance that the board could be the problem?

6

No.

I believe, under Windows, it is possible to overload a serial port (multiple devices assigned the same COM port number). Maybe that is the root cause. I recall a few folks have posted instructions on the forum describing how to eliminate the problem. Unfortunately, I do not have a link at hand.