nad at acm
Nov 8, 2009, 12:21 PM
Post #2 of 2
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Re: pyserial vs. Linux power save hibernate/resume - program hangs
[In reply to]
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In article <4af71b7e$0$1645$742ec2ed[at]news.sonic.net>,
John Nagle <nagle[at]animats.com> wrote:
> I have an application running with pyserial talking to a USB to serial
> converter on a Linux EeePC 2G Surf. This works. Until the lid on the PC is
> closed and the device suspends.
>
> The application has /dev/ttyUSB0 open, and has a read pending
> with a 1 second timeout. When the device comes out of suspend,
> the USB devices are enumerated again. The serial device moves
> to /dev/ttyUSB1, and the application continues to poll /dev/ttyUSB0.
> No error results from polling the removed device. So the
> application is stuck and doesn't know it.
>
> An attempt to write to the disconnected serial port produces
> an IOError exception, but the read side doesn't seem to notice.
If your Linux is new enough, you should be able to create a permanent
device name for the serial converter using a udev rule. Then your code
won't need to be dependent on the /dev/ttyUSBx device name.
--
Ned Deily,
nad[at]acm.org
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