The 7470 Plotter's Instruction Set; Hp-Glsyntax - HP 7470A Interfacing And Programming Manual

The 7470 P1otter's Instruction Set
All three interface configurations for the HP 7470 Plotter use the same
Hewlett-Packard Graphics Language (HP—GL) i nstruction set, with
minor exceptions.* HP—GL consists of two-letter mnemonic instructions
which activate the plotter. A table listing the instructions alphabetically
is located at the end of the next section. Syntax descriptions and
explanations of these instructions are contained in Chapters 1 through
8. Six additional HP—GL instructions cause no operation but are in­
cluded for compatibility with other HP plotters. These instructions are
listed in Appendix C.
Fourteen additional instructions, called device control instructions, are
required by the RS-232-Cconfiguration. These instructions are used to
establish plotter output and handshake protocol, and to control condi­
tions which are pertinent only to the RS-232-Cenvironment. In an
RS-232-C plotter, all HP—GLinstructions enter the p1otter's internal
buffer and are executed in a first—in,first—outsequence. Device control
instructions do not enter the buffer, but instead are executed imme­
diately upon receipt. Refer to Chapter 10for the syntax description and
an explanation of the device control instructions.
HP—GLSyntax
An HP—GL instruction is a two-letter mnemonic, which may be upper­
or lowercase. A command is defined as an instruction followed by its
parameter field, if any, and a terminator. If parameters follow the
mnemonic, they must be separated from each other by at least one
comma or space, or by a + or - sign which may be preceded by commas
or spaces. Optional commas and/ or spaces may be used as separators
before, after, and between the mnemonic and before the terminator. An
instruction is terminated by a semicolon, nonalphabetic and nonnu­
meric characters such as # or $, or by the next mnemonic. If you have
an HP—IB or HP—IL plotter, a line feed can also terminate an instruction.
(Note that if you have an RS-232-Cplotter, a line feed is not a valid
terminator.) Some instructions will execute immediately after the
mnemonic or last required parameter is received. When this is the case,
the designation for the terminator is shown in parentheses in the
syntax description. The syntax is shown on the next page.
*Option 001 provides 45 instructions; Option 002 provides 42 -instructions;
Option 003 provides 41 instructions. Refer to the Plotter Instruction Set table
in this chapter.
1-6 GETTING STARTED