.. _faq: *************************** Frequently asked questions *************************** .. contents:: Summary :depth: 2 :local: :backlinks: top .. _usb_to_centronics_adapters: About the USB/Centronics adapters --------------------------------- .. figure:: _static/misc/usb_lpt_centronics_adapter.webp :scale: 60 % :align: center :alt: usb to centronics printer adapter USB to Centronics Printer Adapter; Yes they can be used to test the interface. They can be used to connect to a Centronics printer or to the |project_name| interface. Provided that this port is configured as an ESC or PCL printer in CUPS. See some examples of drivers for **Epson Dot Matrix & Stylus** printers, and also for **HP Deskjet & LaserJet** PCL printers: EPSON 9-pin Dot Matrix, epson9.ppd ESC/P, B/W, 60x72, 120x72, 240x72 dpi EPSON 24-pin Dot Matrix, epson24.ppd ESC/P, B/W, 120x180, 180x180, 360x180, 360x360 dpi EPSON Stylus Color, stcolor.ppd ESC/P2, B/W/CMYK, 180, 360, 720 dpi EPSON Stylus Photo, stphoto.ppd ESC/P2, B/W/CMYK, 180, 360, 720 dpi HP DeskJet, deskjet.ppd PCL, B/W/CMYK, 150, 300, 600 dpi HP LaserJet, laserjet.ppd PCL, B/W, 150, 300, 600 dpi These drivers are embeded in CUPS as you can see it on their `repository `_. But you can also download them on this website: `Openprinting Epson Dot Matrix `_. About the support of the bridge with modern printers ---------------------------------------------------- |project_name| offers a way to forward the data to be printed to another printer. The support of other printers can be a problem problem but it's not the responsibility of the project because this part is handled by CUPS and its embedded drivers on GNU/Linux distributions. However, it should be noted that new printers are quickly supported (within a few months) and that the standardization of GNU/Linux drivers has made great progress in the last few years. In the worst case manufacturers provide proprietary drivers for their machines. Check this link for GNU/Linux compatible printers via CUPS: `openprinting.org `_. Is the project compatible with RetroPrinter binaries? ----------------------------------------------------- The project is designed as a drop-in replacement for RetroPrinter binaries. It should be noted that (in 2021) of all their binaries only `convert-escp2` (the Epson ESC instruction converter) is the one that is really useful. The other executables are only used to move the print files or to perform minor perform minor actions; they have all been reimplemented in the code of |project_name|. You can reuse the `convert-escp2` executable from Retroprinter as is in the provided disk image without moving it, as long as you enter its path in the configuration file for |project_name| (`/etc/libre-printer/libreprinter.conf`). You can also install the version we package for |project_name|. Note that in the later case the configuration files for the converter are located in XXX (TBR). Can I connect multiple printers/interfaces? ------------------------------------------- Yes! Unlike the Retroprinter project which monopolizes one Raspberry Pi per printer you can support as many printers as available USB ports. See the chapter :ref:`setting_up_multiple_printers` for more info. .. _interface_type: How do I recognise my interface type? ------------------------------------- Note that most DB-25 cables (25 pins) with DB25 connectors at both ends are serial cables. This was the standard RS-232 connector before the more compact DE-9 or erroneously called DB-9 (9-pin) connectors were introduced in the 1980s, and sometimes for other purposes than a serial link (`cf. on Wikipedia: RS-232 `_, `connecteurs D-sub `_). Some ressources for the serial connector pinouts ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - Norms: RS-232, EIA RS-232, EIA 232, TIA 232. - Connector names: DE-9 (male on the DTE (Data Terminal Equipment) side), DB-9 (wrongly named), DB-25 or D-Sub 25 (female on the DTE side). .. figure:: _static/pinouts/DB25_RS232_cable.gif :scale: 75 % :align: center :alt: COM Port pinout DE-9 DB-25, Female port, Computer side COM Port pinout DE-9 DB-25, Female port, Computer side .. figure:: _static/pinouts/DB25_serial_cable_pinout.png :scale: 75 % :align: center :alt: COM Port pinout DB-25, Female port, Computer side COM Port pinout DB-25, Female port, Computer side Sources: `www.aggsoft.com `_, `firewall.cx `__. Some ressources for the Centronics/parallel connector pinouts ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - Norm: IEEE 1284. - Connector names: LPT (Line Printing Terminal), DB-25 or D-Sub 25 (female on the computer side), Centronics or CN36 (female on the printer side). .. figure:: _static/pinouts/LPT_port_pinout.gif :scale: 75 % :align: center :alt: LPT Port pinout DB-25, Female port, Computer side LPT Port pinout DB-25, Female port, Computer side .. figure:: _static/pinouts/Centronics_pinout.png :scale: 90 % :align: center :alt: Centronics Port, CN36, Female port, Printer side Centronics Port, CN36, Female port, Printer side Sources: `firewall.cx `__. Hardware test ~~~~~~~~~~~~~ Test the DTR pin (pin 20) of the DB25 connector with a multimeter. If you found more than 5V on it (and by extension more than 5V on any pin), you have a Serial RS-232 interface. Software test ~~~~~~~~~~~~~ Any configuration option that relates to the notions of **parity**, **number of bits** exchanged or **transfer speed in bauds** means that it is a serial RS-232 interface.