Chapter 3: Controlling The Pen And Plotting; What You'lllearn In This Chapter; Hp-Gl Instructions Covered; Terms Youshould Understand - HP 7470A Interfacing And Programming Manual

Chapter
Controlling the Pen
and Plotting
What You'llLearn in This Chapter
Now that you understand the unit systems in which data can be repre­
sented, you are ready to create plots. In this chapter, you will learn how
to select either of the two pens or change pens, how to set and change
pen velocity, how to raise and lower the pen, and how to plot. You will
learn how to plot to absolute X,Ycoordinates or to plot relative to the
last pen position. Finally, you will learn how to send variables as
parameters of plot commands; this will enable you to write general pur­
pose graphics programs.
HP-GL Instructions Covered
SP The Select Pen Instruction CI* The Circle Instruction
VS The Velocity Select Instruction AA* The Arc Absolute
PU/PD The Pen Up/ Down Instructions Instruction
PA The Plot Absolute Instruction AR* The Arc Relative
PR The Plot Relative Instruction Instruction
Terms YouShould Understand
Absolute Plotting — plotting to a point whose location is specified
relative to the origin (0,0). When the PA command is used to plot to a
point, the pen always moves to the same point on the plotting surface,
no matter where the pen was before the move.
Relative Plotting — plotting to a point whose location is specified
relative to the current pen position. The point moved to then becomes
the effective origin for the next parameter of a plot relative command.
When the PR command is used to plot to a point, the destination of the
pen depends on where the pen was when the command was received.
>Plotter Unit Equivalent —the X,Ycoordinates of a point, given in user
units, if they were expressed in plotter units.
*Available only with Option 001 plotters that have the serial prefix number
2308Aor higher.
CONTROLLING THE PEN AND PLOTTING 3-I