I own a HP color LaserJet 2550n since a few days now and I needed quite some time to find out the things listed below. These hints are mainly listed here to make life easier for others. I've configured the printer with SUSE LINUX 9.2, but in principle the following should be valid for all Linux distributions.

Advertisment and manual tells you that the HP LaserJet 2550 Series is capable of printing 20 pages per minute in black and white printing mode. I installed two printer queues with cups, one was named printer_color, the other one printer_bw. I choosed the printer model 'HP Color LaserJet 2550Series' in the YaST2 printer dialog for both queues. I configured the bw queue with the setting `Print Color as Gray' as 'yes' and the color queue with this option set to no. This way I wanted to save time and resources for black and white prints.

Nevertheless the printouts were black and white, but (you can hear the printer mechanics working and also from the time consumption) this was done in the color mode of the printer, with around 4 pages per minute.

Solution: Obviously only PCL data is printed in pure black and white mode. I reconfigured the printer_bw queue to use the PCL only printer HP LaserJet 6P. For black and white prints the computer uses ghostscript to convert the postscript data into PCL and greyscale. This way the printer prints with the around 20 pages per minute (which is quite fast).

There seems to be no obvious possibility to get the remaining lifetime of imaging drum or toner cassettes from within Linux. Fortunatly the printer is compatible to RFC 1759. This information can be gathered using SNMP.

Solution: I wrote a small perl application, that can be called directly on the command line. Only the CPAN module Net::SNMP is necessary. The script is called Poll-HP-Supplies.pl and is quite short and simple.