On Sun, Mar 07, 2010 at 07:17:04AM -0500, Paul Alfille wrote:
> > I'm migrating from digitemp and with digitemp if I was getting errors with
> > my serial or USB adapter or bus, I got clear errors from the program.
> >
>
> Great, but digitemp and owfs have quite different approaches. Digitemp is
> really meant to run in foreground and diagnose, while OWFS runs mostly in
> the background as a service to other programs. That makes reporting more
> difficult.
Yes, I do realize that, that's why I asked :)
> > With owfs, I didn't find a clear explanation of what happens if I'm trying
> > to read a temperature from the virtual filesystem, and:
> >
> > - bus is too long/unstable and the read yields a CRC error
>
> After 3 attempts (like digitemp) you get an error returned (EINVAL). There
> are error statistics under statistics/bus/... and statistics/read/... that
> can be monitored to see if the hardware is marginal. There is a program
> (owmon) that is supposed to show the errors in the foreground, but I haven't
> tested it recently.
Cool.
> > - the 1 wire bus gets unplugged from the interface, so all devices
> > disappear
> >
> You can an error (and all the devices disappear. Again there are errors in
> statistics, and lots of data if you run with debugging on.
Right, so the read would fail, good to know.
> > - the USB interface (DS2490) locks up
> >
> I'm not sure what you mean by locks up. Unplgged? replugged?
You might not have that problem with owfs. With digitemp, marginal bus
conditions caused the interface to lock up and it has to be physically power
cycled to recover (required a usb hub that actually let you shut down power
to a port).
> > - the serial interface (DS9097U) has some other kind of error
> >
> > I realize that something will likely end up in the logs for this, but what
> > happens to my read system call on the temperature file in the 4 different
> > cases listed above?
> >
> Error and timeouts.
Thanks for the answers. That should work when I get the serial interface to
work then.
Marc
--
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems & security ....
.... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/
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