| openSUSE Documentation Chapter 7. Printer Operation / 7.8. Troubleshooting | ||||
|---|---|---|---|---|
 | 7.7. Special Features in openSUSE | Chapter 8. The X Window System |  | |
| openSUSE Documentation Chapter 7. Printer Operation / 7.8. Troubleshooting | ||||
|---|---|---|---|---|
| 7.7. Special Features in openSUSE | Chapter 8. The X Window System | | |
The following sections cover some of the most frequently encountered printer hardware and software problems and ways to solve or circumvent these problems. Among the topics covered are GDI printers, PPD files, and port configuration. Common network printer problems, defective printouts, and queue handling are also addressed.
These printers do not support any common printer language and can only be addressed with special proprietary control sequences. Therefore they can only work with the operating system versions for which the manufacturer delivers a driver. GDI is a programming interface developed by Microsoft* for graphics devices. Usually the manufacturer delivers drivers only for Windows and because the Windows driver uses the GDI interface, these printers are also called GDI printers. The actual problem is not the programming interface, but the fact that these printers can only be addressed with the proprietary printer language of the respective printer model.
Some GDI printers can be switched to operate either in GDI mode or one of the standard printer languages. See the manual of the printer whether it is possible. Some models require a special Windows software to do the switch (note that the Windows printer driver may always switch the printer back into GDI mode when printing from Windows). For other GDI printers there are extension modules for a standard printer language available.
Some manufacturers provide proprietary drivers for their printers. The disadvantage of proprietary printer drivers is that there is no guarantee that these work with the installed print system and that they are suitable for the various hardware platforms. In contrast, printers that support a standard printer language do not depend on a special print system version or a special hardware platform.
Instead of spending time trying to make a proprietary Linux driver work, it may be more cost-effective to purchase a supported printer. This would solve the driver problem once and for all, eliminating the need to install and configure special driver software and obtain driver updates that may be required due to new developments in the print system.
If the manufacturer-PPDs package does not contain
any suitable PPD file for a PostScript printer, it should be possible to
use the PPD file from the driver CD of the printer manufacturer or download
a suitable PPD file from the Web page of the printer manufacturer.
If the PPD file is provided as a zip archive (.zip) or a self-extracting
zip archive (.exe), unpack it with
unzip. First, review the license terms of the PPD file.
Then use the cupstestppd utility to check if the PPD
file complies with “Adobe PostScript Printer Description File Format
Specification, version 4.3.” If the utility returns
“FAIL,” the errors in the PPD files are serious and are likely
to cause major problems. The problem spots reported by
cupstestppd should be eliminated. If necessary, ask the
printer manufacturer for a suitable PPD file.
The safest approach is to connect the printer directly to the first parallel port and to select the following parallel port settings in the BIOS:
I/O address: 378 (hexadecimal)
Interrupt: irrelevant
Mode: Normal, SPP, or
Output Only
DMA: disabled
If the printer cannot be addressed on the parallel port despite these
settings, enter the I/O address explicitly in accordance with the setting
in the BIOS in the form 0x378 in
/etc/modprobe.conf. If there are two parallel ports
that are set to the I/O addresses 378 and
278 (hexadecimal), enter these in the form
0x378,0x278.
If interrupt 7 is free, it can be activated with the
entry shown in
Example 7.1, “
/etc/modprobe.conf: Interrupt Mode for the First
Parallel Port
”. Before activating the
interrupt mode, check the file /proc/interrupts to see
which interrupts are already in use. Only the interrupts currently being
used are displayed. This may change depending on which hardware components
are active. The interrupt for the parallel port must not be used by any
other device. If you are not sure, use the polling mode with
irq=none.
Example 7.1.
/etc/modprobe.conf: Interrupt Mode for the First
Parallel Port
alias parport_lowlevel parport_pc options parport_pc io=0x378 irq=7
Connect the printer directly to the computer. For test purposes, configure the printer as a local printer. If this works, the problems are related to the network.
The TCP/IP network and name resolution must be functional.
By default, the cupsd only listens on internal network interfaces
(localhost). Check whether the
Listen directive(s) in
/etc/cups/cupsd.conf allow access from the
outer network:
Listen 192.168.2,*:631
A CUPS server either needs to be in the internal firewall zone or, when being in the external zone, must be able to send and receive data on the UDP and TCP port 631.
Use the following command to test if a TCP connection
can be established to lpd (port
515) on host:
netcat -z host 515 && echo ok || echo failedIf the connection to lpd cannot be established, lpd may not be active or there may be basic network problems.
As the user root, use the
following command to query a (possibly very long) status report for
queue on remote
host, provided the respective
lpd is active and the host accepts queries:
echo -e "\004queue" \
| netcat -w 2 -p 722 host 515
If lpd does not respond, it may not be active or
there may be basic network problems. If lpd
responds, the response should show why printing is not possible on the
queue on host. If you receive a
response like that in Example 7.2, “Error Message from lpd”, the problem is caused
by the
remote lpd.
Example 7.2. Error Message from lpd
lpd: your host does not have line printer access lpd: queue does not exist printer: spooling disabled printer: printing disabled
By default, the CUPS network server should broadcast its queues every 30
seconds on UDP port 631. Accordingly, the following
command can be used to test whether there is a CUPS network server in
the network.
netcat -u -l -p 631 & PID=$! ; sleep 40 ; kill $PID
If a broadcasting CUPS network server exists, the output appears as shown in Example 7.3, “Broadcast from the CUPS Network Server”.
The following command can be used to test if a TCP connection can be
established to cupsd (port 631) on
host:
netcat -z host 631 && echo ok || echo failed
If the connection to
cupsd cannot be established, cupsd
may not be active or there may be basic network problems.
lpstat -h host -l -t
returns a (possibly very long) status report for all queues on
host, provided the respective
cupsd is active and the host accepts queries.
The next command can be used to test if the
queue on host
accepts a print job consisting of a single carriage-return character.
Nothing should be printed. Possibly, a blank page may be ejected.
echo -en "\r" \
| lp -d queue -h hostSpoolers running in a print server box sometimes cause problems when they have to deal with a lot of print jobs. Because this is caused by the spooler in the print server box, there is nothing you can do about it. As a work-around, circumvent the spooler in the print server box by addressing the printer connected to the print server box directly with TCP socket. See Section 7.4, “Network Printers”.
In this way, the print server box is reduced to a converter between the
various forms of data transfer (TCP/IP network and local printer
connection). To use this method, you need to know the TCP port on the
print server box. If the printer is connected to the print server box
and powered on, this TCP port can usually be determined with the
nmap utility from the nmap
package some time after the print server box is powered on. For example,
nmap IP-address may
deliver the following output for a print server box:
Port State Service 23/tcp open telnet 80/tcp open http 515/tcp open printer 631/tcp open cups 9100/tcp open jetdirect
This output indicates that the printer connected to the print server box
can be addressed via TCP socket on port 9100. By
default, nmap only checks a number of commonly known
ports listed in /usr/share/nmap/nmap-services. To
check all possible ports, use the command nmap
-p from_port-to_port IP-address.
This may take some time. For further information, refer to the man page
of nmap.
Enter a command like
echo -en "\rHello\r\f" | netcat -w 1 IP-address port cat file | netcat -w 1 IP-address port
to send character strings or files directly to the respective port to test if the printer can be addressed on this port.
For the print system, the print job is completed when the CUPS back-end completes the data transfer to the recipient (printer). If the further processing on the recipient fails, for example, if the printer is not able to print the printer-specific data, the print system does not notice this. If the printer is not able to print the printer-specific data, select a different PPD file that is more suitable for the printer.
If the data transfer to the recipient fails entirely after several
attempts, the CUPS back-end, such as USB or
socket, reports an error to the print system (to
cupsd). The back-end decides whether and how many
attempts make sense until the data transfer is reported as impossible.
Because further attempts would be in vain, cupsd
disables printing for the respective queue. After eliminating the cause of
the problem, the system administrator must reenable printing with the
command /usr/bin/enable.
If a CUPS network server broadcasts its queues to the client hosts via browsing and a suitable local cupsd is active on the client hosts, the client cupsd accepts print jobs from applications and forwards them to the cupsd on the server. When cupsd accepts a print job, it is assigned a new job number. Therefore, the job number on the client host is different from the job number on the server. Because a print job is usually forwarded immediately, it cannot be deleted with the job number on the client host, because the client cupsd regards the print job as completed as soon as it has been forwarded to the server cupsd.
To delete the print job on the server, use a command such as lpstat -h cups.example.com -o to determine the job number on the server, provided the server has not already completed the print job (that is, sent it completely to the printer). Using this job number, the print job on the server can be deleted:
cancel -h cups.example.com queue-jobnnumberPrint jobs remain in the queues and printing resumes if you switch the printer off and on or shut down and reboot the computer during the printing process. Defective print jobs must be removed from the queue with cancel.
If a print job is defective or an error occurs in the communication between the host and the printer, the printer prints numerous sheets of paper with unintelligible characters, because it is unable to process the data correctly. To deal with this, follow these steps:
To stop printing, remove all paper from ink jet printers or open the paper trays of laser printers. High-quality printers have a button for canceling the current printout.
The print job may still be in the queue, because jobs are only removed
after they are sent completely to the printer. Use lpstat
-o or lpstat -h cups.example.com -o to check
which queue is currently printing. Delete the print job with
cancel
queue-jobnumber
or cancel -h cups.example.com
queue-jobnumber.
Some data may still be transferred to the printer even though the print job has been deleted from the queue. Check if a CUPS back-end process is still running for the respective queue and terminate it. For example, for a printer connected to the parallel port, the command fuser -k /dev/lp0 can be used to terminate all processes that are still accessing the printer (more precisely: the parallel port).
Reset the printer completely by switching it off for some time. Then insert the paper and turn on the printer.
Use the following generic procedure to locate problems in the CUPS print system:
Set LogLevel debug in
/etc/cups/cupsd.conf.
Stop cupsd.
Remove /var/log/cups/error_log*
to avoid having to search through very large
log files.
Start cupsd.
Repeat the action that led to the problem.
Check the messages in /var/log/cups/error_log* to
identify the cause of the problem.
Solutions to many specific problems are presented in the SUSE Support
Database (http://en.opensuse.org/SDB:SDB). Locate the
relevant articles with a text search for SDB:CUPS.
