The Arc Absolute Instruction, Aa - HP 7470A Interfacing And Programming Manual

The Arc Absolute Instruction, AA
DESCRIPTION The are absolute instruction, AA, provides the means
to draw an arc with the center point located at a specified absolute
point. The are can be drawn clockwise (CW) or counterclockwise (CCW),
subtends the specified are angle, and conforms to the specified or
default chord angle. It is only included in the instruction set of RS-232-C
plotters that have the serial prefix number 2308A or higher.
M The instruction can be used to draw an arc of any radius,
length, and smoothness with a single command. The are is drawn from
the current pen position, and its center point is located by absolute X,Y
coordinates.
SYNTAX AA X—coordinate,Y-coordinate, arc angle (, chord angle)
terminator
CURQENT pEN ABSOLUTE X, Y
/L pOs|T|oN cooRDINATES (ARC CENTER)
/ CHORD ARC ANGLE
ANGLE
K ABSOLUTE x,v
T COORDINATES CURRENT
(ARC CENTER) PEN
POSITION
\ CHORD
ANGLE
EXPLANATIONThe AA instruction requires that both X- and Y­
coordinates be specified (coordinate pair) in integer format. They are
interpreted as plotter units if scaling is off or as user units if scaling is
on. The X- and Y—coordinateslocate the center of the arc and may be
located on or off the plotting surface. The current pen position is the
starting point of the arc.
The are angle is in integer format. It is the angle, in degrees, through
which the arc is drawn: a positive arc angle draws CCW from the
current pen position; a negative arc angle draws CW from the current
pen position.
The chord angle parameter is in integer format and governs the
smoothness of the arc in the same way as defined under the circle
instruction, CI. The sign of the parameter is ignored, except to set the
maximum in-range limit to -32 768 or +82 767. The default chord angle
is 5 degrees.
Unlike circles, arcs are drawn using the previously commanded pen
state (up or down) and line type. If no pen state has been commanded
CONTROLLING THE PEN AND PLOTTING 3-17