The Output Commanded Position And Pen Status - HP 7470A Interfacing And Programming Manual

The Output Commanded Position and
Pen Status Instruction, OC
DESCRIPTIONThe output commanded position and pen status instruc­
tion, OC, is used to output the X— and Y-coordinates and pen status (up
or down) associated with the last valid pen position command.
ma This instruction can be used to determinethe pen'slast valid
commanded position in plotter units or user units depending on whether
scaling is off or on. You might use that information to position a label
or figure, or determine the parameters of an instruction which moved
the pen to the limits of some window.
SYNTAX OC (terminator)
EXPLANATIONOutput is in decimal format, in user units when scaling
is in effect, and in plotter units when scaling is off.
N0 parameters are used. The instruction will execute even if no termi­
nator is received.
The pen position and status are output to the computer as decimal
numbers in ASCII in the form:
X,Y,P [TERM]
where X is always the X—coordinate i n plotter units or user units,
Y is always the Y-coordinate in plotter units or user units,
P is the pen status (0 = pen up, 1 = pen down), and
[TERM]is the output terminator for the interface installed.
When scaling is off, X— and Y-coordinates are in plotter units. When
scaling is on, X— and Y—coordinates are in user units. Ranges of the
X-and Y—coordinatesare -32 768 to 32 767 whether scaling is on or off.
NOTE: If you have an HP-IB or RS-232—C plotter that has the serial
prefix number 2308A or higher, or if you have an HP-IL plotter, output is
in decimal format as described above. All HP-IB or RS-232-C plotters
with a lower prefix serial number output integer parameters, as
follows. When scaling is on, X- and Y—coordinatesare always rounded
to the nearest integer value. Thus, while plotting can occur to noninte—
ger Values, output of pen position can only be obtained to the nearest
integer value. I
When the commanded pen position is such that its user unit value
would be less than -32 768 or greater than 32 767, the output may not
represent the true pen position. If the plotter were scaled with the given
instructions as shown in the following illustration, all points in the
lightly shaded area will have one coordinate as 32 767, the largest
number the plotter can output. All points in the darker shaded area will
have both coordinates as 32 767.
7-4 OBTAINING INFORMATION FROM THE PLOTTER