HP 5961-0509 manual What are Printer Commands?, Control Codes, PCL Commands

What are Printer Commands?

PCL printer commands provide access to printer features. There are four general types of HP printer language commands:

z control codes z PCL commands

z HP-GL/2 commands z PJL commands

	Control Codes
	A control code is a character that initiates a printer function, for
	example Carriage Return (CR), Line Feed (LF), Form Feed (FF), etc.
	PCL Commands
	PCL commands provide access to the printer’s PCL control structure.
	The PCL structure controls all of the printer’s features except those
	used for vector graphics, which are controlled by the HP-GL/2
	commands.
	PCL printer commands consist of two or more characters. The first
	character is always the ASCII escape character, identified by the ?
	symbol. ? is a special control code which identifies the subsequent
	string of characters as a printer command. As the printer monitors
	incoming data from a computer, it “looks” for this character. When this
	character appears, the printer reads it and its associated characters
	as a command to perform and not as data to print.
Note	PCL printer commands (other than single-character control codes)
	are also referred to as escape sequences. The terms printer
	command and escape sequence are used interchangeably
	throughout this manual.
	Once a PCL command sets a parameter, that parameter remains set
	until that PCL command is repeated with a new value, or the printer is
	reset to its user default environment. For example, if you send the
	printer a command to set line spacing to 3 lines/inch, each page
	prints 3 lines/inch until the printer receives a different Line Spacing
	command, or the printer is reset.

EN What are Printer Commands? 1-3