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 since 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 in one of the standard printer languages. See the manual of the printer whether this is possible. Some models require 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 or 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 11.1, “/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 11.1. /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.
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 shown in Example 11.2, “Error Message from lpd”,
the problem is caused by the remote lpd.
Example 11.2. 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. Make sure to stop your local CUPS daemon
before executing the command.
netcat -u -l -p 631 & PID=$! ; sleep 40 ; kill $PID
If a broadcasting CUPS network server exists, the output appears as shown in Example 11.3, “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 multiple print jobs. Since this is caused by the spooler in the print server box, there no way to resolve this issue. As a work-around, circumvent the spooler in the print server box by addressing the printer connected to the print server box directly with the TCP socket. See Section 11.4, “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 turned 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 up. 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 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 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 determines how many unsuccessful
attempts are appropriate until the data transfer is reported as
impossible. As 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 cupsenable.
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. As a print job is usually forwarded immediately, it cannot be deleted with the job number on the client host This is because the client cupsd regards the print job as completed as soon as it has been forwarded to the server cupsd.
When it becomes desirable 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-jobnnumberif you switch the printer off or shut down the computer during the printing process, print jobs remain in the queue. Printing resumes when the computer (or the printer) is switched back on. 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 rectify this situation, 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.