@soren Sorry for the late reply. Atom currently always copies the top option in the list. If there is an actual Pycom serial detected, it will place that one at the top. Anyway, this is just a result of your issue, not the cause. So just to be sure, after rebooting your mac, you are able to connect to your device? Then when switching out to a different lopy, the comport disappears from the list of serials, even when closing the connection during the swap? Do you switch expansionboards, or just the lopy? You could even hot-swap your lopy while keeping the expansion board connected, see if that helps.

@jmarcelino $ ioreg -p IOUSB +-o Root <class IORegistryEntry, id 0x100000100, retain 15> +-o Root Hub Simulation Simulation@14000000 <class AppleUSBRootHubDevice, id 0x10000034b, registered, matched, active, busy 0 (0 ms), retain 10> +-o Bluetooth USB Host Controller@14300000 <class AppleUSBDevice, id 0x1000003f2, registered, matched, active, busy 0 (1 ms), retain 21> +-o FT230X Basic UART@14100000 <class AppleUSBDevice, id 0x1000005dd, registered, matched, active, busy 0 (15 ms), retain 14> This is the output when the wipy is connected, and right now it's working fine. I'll run the command again if the problem re-occurs. Thanks, Bernhard

@jmarcelino Thanks Will check Homebrew info you provided out. Worked out of box on a Linux box that one of the dev's uses and he owns that project for now so the heat is off for a while ;)