Problem closing non-responsive USB-serial ports

Sarah Reichelt sarah.reichelt at
Mon Mar 10 19:36:11 EDT 2008

Hi All,

I am having a weird problem that may actually be faulty hardware, but
I think Rev should be handling it better anyway. I have an app that
communicates with a serial device via a USB-serial adapter. This works
very well most of the time, but on one particular computer, the USB
ports drop out every now & then. I have scripts that detect when the
serial device is not responding, they try again once and then they try
resetting the port by closing it & re-opening it. However it never
gets past the closing of the port.

This is on OS X and I use the "close driver" command, with the driver
name that was stored when the port was opened. It is enclosed in a
"try" structure and it never gives an error, but never completes. It
then takes numerous force-quits to get rid of the app and a full
restart is needed to get the communications working again.

So I may have a computer with a dodgy USB bus, but surely I should be
getting an error message rather than just hanging. I tried sending a
timed message before starting to close the port, but this never
happens either, so Rev really gets completely stuck trying to close a
non-responsive serial port.

Has anyone experienced anything similar? Is it worth a bug report? And
do any of you have any suggestions as to what I could try next apart
from switching this app to another computer which I plan to do next


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