serial port re-enumerates every upload.

HI Everyone,

I have a problem I have not seen before – wondering if others have had this experience? ANd if so is a solution known?

I teach a class in basic electronics, a student running OSX 10.11.6 and Arduino 1.8.5 is having a serial port problem with Arduino pro micro and Uno rev3. I have confirmed the problem – same boards on my machine (10.10.5) do not behave this way.

While code upload and serial monitor work, the port is acting odd.

Every time they upload code, the serial port disconnects after upload, and reconnects with new interface number (please see attached screen grab of OSX network preferences after several uploads.)

Similarly, after resetting PORT and open serial monitor causes reenumeration.

The result is a workflow that goes something like upload – TOOLS–> ports – serial moitor – tools–>ports, upload tool-ports … Cable is not disconnected at any time.

I am familiar with ports switching occasionally on OSX-- but usually between 2 interfaces – not a new indexed interface every time.

The situation is unstable and prohibitively frustrating.

Can anyone give me an idea of how to solve this? Is this a driver conflict? Similar to USB3 incompatibility? Apple finding new ways to make things that just work, now break? Arduino reinstall did not help.

Thanks for your time.

steve

PortIssue1.pdf (78.8 KB)

PortIssue2.pdf (51.7 KB)