Configuring Nonsupported Printers

A nonsupported printer is a device that is not supplied with the operating system.

Configuration Options

Choose one of the following methods to configure and drive a nonsupported printer:

• Configure the device as a supported printer if the nonsupported printer uses the same hardware interface (serial or parallel) and closely approximates the functions of a supported printer.
• Configure your printer as a supported printer if there are no supported printers similar to yours. Change the virtual printer characteristics to accommodate your printer.
• Use generic as the printer type and the appropriate interface type if you are unsure if your printer emulates a supported device. The operating system supplies two generic devices, other parallel printer (opp) and other serial printer (osp). Specify one of these devices by selecting the interface type, such as parallel rs232, and modify the characteristics according to the specifications in your printer manual.
• Configure your printer device driver and print queue, but set the print subsystem to pass all print requests transparently to the printer. With this configuration the application must correctly assemble the printer data stream. The print spooling subsystem is available for sharing the printer among users, but the virtual printer system does not format the printer data stream.
• If your output device has special formatting requirements, such as an electrostatic plotter that requires input as raster graphics, substitute the formatting software for the printer formatter or the printer backend program.

Customizing Nonsupported Virtual Printers

You must define a virtual printer to support the features of the nonsupported printer and the print spooling subsystem.

1. You must identify the printer data stream that best matches your printer to customize a nonsupported printer. The operating system supports the following data streams through predefined virtual printers:

   asc	Extended ASCII
   pcl	Hewlett-Packard LaserJet
   gl	Plotter
   ps	PostScript
   630	Diablo 630
   855	Texas Instruments 855 dot matrix printer in dp mode

2. Once you have identified the data stream used by your printer, choose either a supported printer that uses the same data stream or one of the generic printers and customize the definition for your printer.

Wiring Nonsupported Printers

You may need to adapt your nonsupported printer so that it functions properly with the AIX serial printer device driver:

1. The following chart details what the RS-232 signals mean to the serial printer device driver:

   RS-232 Signal	Serial Printer Device Driver Use
   FG	Frame ground. Often used as shield.
   TxD  -->	Used to transmit data to printer.
   RxD  <--	Used to Receive data from printer.
   RTS  <--	Held high after printer port opened. Provides host status to printer. Not used for data pacing.
   CTS  <--	Must be high for printer port to be opened. Used to detect that the printer is turned on.
   DSR	Not used. Usually tied to DCD.
   SG	Reference voltage for signals.
   DCD  <--	Used for data pacing when DTR is set to yes.
   DTR  -->	Held high after printer port opened. Provides host status to printer.

2. If you use FG as a cable shield, make sure that it is only connected at one end. It makes no difference which end is connected. This provides an efficient shield against electrical noise.

3. If your RTS signal is used to supply voltage to CTS on the printer port, check to see what your printer does with its RTS signal.

   Although RTS and CTS data pacing is not supported on serial printers, the device driver will block the open of the printer port until the voltage of CTS becomes high. The CTS signal is usually supplied by the RTS signal from the printer. However, some printers use the RTS signal for data pacing. These printers drop RTS when they want the system to stop sending data. Since the queuing system always needs the port opened to check for status, if the printer drops the RTS signal, the port closes and the queue goes down.

4. Some printers require that you raise the voltage of DCD and DSR or CTS on the printer side. There are several methods for raising the voltage:
   • Use DTR or RTS on the computer side to supply the voltage.

     OR

   • Obtain the voltage from the printer side.