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Topic: USB-Serial adapter gets "lost" (Read 5206 times) previous topic - next topic


(This is on OS X 10.6.8)

Two or three times now, something has happened while using the Arduino development package that's just odd. It may be related to unplugging/plugging the adapter while the Arduino app is running, or maybe disconnecting while the Serial Monitor is running; I don't know, but sometimes after the disconnect/reconnect, when I try to download a sketch or open the Serial Monitor, I get the message "Serial port '/dev/tty.SLAB_USBtoUART' not found."

Quitting and relaunching the Arduino app doesn't help. Further, the USB adapter is no longer listed under Tools/Serial Port, and it is not on the list in /dev; unplugging/replugging the adapter won't bring it back.

Attempting to unload the driver fails because it "is in use", even though I have killed the Arduino app.

So far, the only way I've found to get things running again is to reboot the Mac; very annoying.

I have tried to come up with a reliable way to cause the problem, but haven't been successful so far.

Any suggestions about how to eliminate the problem, or reliably replicate it?



The exact same thing happens in Windows, the only way out is to reboot.



This can be caused by unplugging while the Serial Monitor is open.  I've usually found that I can get the USB-Serial to talk again, but it will be on a different port.

You may be able to end the Serial Monitor task to get out instead of rebooting.  Task Manager in Windows.


I found if you go into Device Manager, right-click the Arudino device (or USB -> Serial adapter device), Disable, then Enable, it will be listed again in the Arudino IDE menu. Faster than a reboot anyway.


That's probably FT232 going crazy. I have similar issues (but never had to reboot, unplugging-reinserting usb and restarting serial monitor was enough). It seems to be is very sensitive to transients. A bulky 50Hz transformer being unplugged always generates a transient, unless it has a grounded shield inside the coil (quite rarely).

Sometimes, a ferrite bead over the usb cable helps. In my case, when I use a good switching power supply, there are no problems.

I still cant figure out how to protect the FT232 from these transients (I make my own boards).



I have definitely seen this problem in Windows (7). I found that it was a power problem. I my Arduino had a heavy power draw (an LED strip in my case) attached to it, the serial connection (COMt6 in my case) was very, very flaky. Detaching the LED strip made the serial connection very stable.

I was able to keep the LED strip attached and keep the serial connection stable by adding an external 5V power supply to my Arduino.

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