[KLUG Members] Brother printer inconsistency

[Peter Bart]

Daniel Hedlund wrote:
> Your printer port settings seem fine to me, so your problem must be
> related to something else.  With issues were related to using a
> Fedora-based system which uses a HAL (hardware abstraction layer) to
> uniquely identify each printer.  The idea with the HAL layer is that
> if I was to have two printers plugged in at the same time, Linux would
> be smart enough to know which of the two printers I was referring to
> when I chose the "Brother HL-1440" printer to print to, instead of for
> example sending it to a HP InkJet.  If you were to have two printer
> connected to two different USB devices, using /dev/usb/lp0 and
> /dev/usb/lp1, it just wouldn't work properly; the first printer that
> was plugged in at any given time would be allocated lp0, regardless of
> whether the drivers matched up or not.
>
> Your cups settings seem okay in that if you have only one printer
> attached, /dev/usb/lp0 is always chosen and your problem shouldn't be
> with port naming.  My problem was a printer attached to a print server
> running on a dodgy laptop with a broken screen and a dodgy network
> card.  I would often have to restart the computer to get networking
> support again and sometimes didn't have the time so I would disconnect
> the printer from the USB and attach it directly to the computer I
> wanted to print from.  When I'd reattach the printer or restart the
> computer, there was sometimes a chance that it would attach with a
> different HAL device name and cause me headaches.
>
> Your problem with your printer is probably related to the printer
> going offline according to cups and not reinitializing its status to
> cups as being online again.  If you were to go into the cups interface
> (http://localhost:631/), you might find that your printer says its
> status is "offline" for example.  Normally you would have to click on
> "Start Printer" and everything would continue where it left off?  If
> that's the case then it's just a problem with your USB printer
> updating the cups status.  My USB printer(s) used to not update their
> CUPS status when plugged in, but after upgrading my distro a version
> or two, it has since started updating automatically.  I think the
> updates are working because of the D-BUS and/or possibly HAL related
> interfaces in my distribution (maybe CUPS is now HAL aware).  Either
> CUPS is polling the USB port occasionally now or there is some hook
> somewhere that finally telling CUPS to change its status.  I haven't
> looked into this in any detail.  Each Linux distro is different at the
> moment in how it's handling system events and/or messages.  Some
> distros are still using udev, some hotplug, some HAL.  It's a big mess
> at the moment and will eventually become standardized and consistent
> across distros.  Until that point, it's very difficult for
> applications to properly hook things together at the system level.
>
> Cheers,
>
> Daniel Hedlund
> daniel at digitree.org 
Daniel,
    Thanks very much for the lesson. I use SUSE 10.0 so I do not have
the HAL and that also clears up a lot of my questions. Next time I have
a problem I will check cups to see if I need to restart the printer.
Like you, what I've done so far; and I think this might be my problem;
is to unplug my Belkin powered usb hub and plug the printer in direct.
Then I shift it back to the hub afterwards and everything's okay?? It's
a much smaller problem than the power issues and Palm connectivity
issues I have. It's interesting to know that about system events, I
believe mine uses udev. Standardization would be nice, those final
tweaks to get everything just right might be a little easier.
Peter


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