Unable to print / backc hannel error

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kjelin
Posts: 2
Joined: Wed Aug 20, 2014 10:32 am

Unable to print / backc hannel error

Post by kjelin » Wed Aug 20, 2014 11:14 am

Hi

I can no longer print on my Canon MP970, using Turboprint. It was working, but then I obviously made the mistake by install (or reinstall) cups-backend-bjnp, using the command "sudo apt-get install cup...". At least that is what I beleave is responsible for my problems printing.

When I'm trying to print something (eg. a testpage) the job hangs in Turboprints monitor (se attached screen dump) and the following text is added to /var/log/cups/error_log:

Code: Select all

C [20/Aug/2014:13:07:29 +0200] [Job 72] bjnp_backchannel: (recv) could not read response header, received 4 bytes!
C [20/Aug/2014:13:07:29 +0200] [Job 72] bjnp_backchannel: (recv) error: Success!
E [20/Aug/2014:13:07:29 +0200] [Job 72] failed to read backchannel data: Success
Can you help me, please?

Regards
Brian

Screen dump:
[img]TurboPrintPrinterMonitor_009.png[/img]
Attachments
TurboPrintPrinterMonitor_009.png
TurboPrintPrinterMonitor_009.png (67.67 KiB) Viewed 6559 times

zedonet
Site Admin
Posts: 1908
Joined: Fri Oct 06, 2006 8:02 am

Re: Unable to print / backc hannel error

Post by zedonet » Wed Aug 20, 2014 1:47 pm

Hello,

the problem is the cups backend "bjnp" (bubble jet network protocol) that is responsible for network data transport to Canon inkjet printers. On some Linux distributions a version of bjnp is preinstalled that doesn't work with all Canon printers. I recommend to replace the file

/usr/lib/cups/backend/bjnp

with the version supplied with TurboPrint that can be found in

/usr/share/turboprint/lib

kjelin
Posts: 2
Joined: Wed Aug 20, 2014 10:32 am

Re: Unable to print / backc hannel error

Post by kjelin » Thu Aug 21, 2014 1:40 pm

Thank you very, very much! That was exactly what I needed to fix the problem.
The bjnp file was btw. located at /usr/lib/turboprint/ and not in /usr/share/turboprint/lib, but your precise answer gave me the all the information I needed to solve the problem anyway.
Have a nice weekend.

RalfG
Posts: 2
Joined: Mon Mar 06, 2017 9:43 pm

Re: Unable to print / backc hannel error

Post by RalfG » Mon Mar 06, 2017 9:52 pm

Unfortunately I´ve got the same error and in spite of replacing the original bjnp file by turboprints version it resulted into the same error : "failed to read backchannel data: Operation now in progress". Do you have any further hints?

zedonet
Site Admin
Posts: 1908
Joined: Fri Oct 06, 2006 8:02 am

Re: Unable to print / backc hannel error

Post by zedonet » Wed Mar 08, 2017 11:33 am

Hello RalfG,

can you please check what version of the BJNP backend is installed? The version should be printed out with the command "/usr/lib/cups/backend/bjnp -v" from a terminal/shell window. The current version included in TurboPrint is "0.55zedo".
As the BJNP backend is maintained by a different developer, I suggest to download the latest version of it from "https://sourceforge.net/projects/cups-bjnp/". I found an entry in a different forum where a similar problem with an MX720 printer is reported that should be fixed with a newer BJNP release. Please note that the download is source code which must be compiled first, just follow the simple instructions in the README file there. Do not forget to copy or install the resulting bjnp file afterwards to the correct destination (as explained in README).

Please also check if the selected printer driver is correct, e.g. "Canon Pixma MX720series" for the Pixma MX 725. Some Canon printers also support the "socket / jetdirect" protocol which would use a different backend. As an alternative you could check if the problem is also present when connecting the printer via USB cable (to find out if the problem is actually backend related).

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