HP 7470A Interfacing And Programming Manual page 39

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)
A default instruction, DF, or an initialize instruction, IN, will also reset
) the velocity and acceleration to the values 38.1 cm/s and 2 g.
• l i e Plot Absolute Instruction, PA
The plot absolute instruction, PA, moves the pen to the
point(s) specified by the X- and Y-coordinate parameters.
IlKlM The instruction can be used together with PD to draw lines or
with PU to move the pen to a specific point on the plot. The instruction
can be executed without parameters to establish absolute plotting, as
opposed to relative plotting for PU or PD commands with parameters.
In this case, the parameters of PU and PD are interpreted as absolute
X,Y coordinates until any PR command is received.
J M i f i H PA Xicoordinate.Yi coordinate (,X2 coordinate,Y2
coordinate X
n
coordinate, Y
n
coordinp.teXterminator)
or
PA (terminator)
Recommended parameters are decimal numbers be­
tween -32 768.0000 and 32 767.9999. When scaling is off, parameters
are truncated to integers as follows:
• For positive numbers, the fractional portion is discarded and the in­
teger portion remains unchanged. For example, both 1234.4 and
1234.9 become 1234.
• For negative numbers, the fractional portion is discarded and the in­
teger portion is changed to the next more negative integer. For ex­
ample, both -1234.4 and -1234.9 become -1235. Since you cannot
plot to negative values unless scaling is on, (in which case decimal
portions of parameters are used), the only time you will observe this
is when you use the output commanded position and pen status
instruction, OC, and the last X- and/or Y-parameter sent was negative.
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, you will
not observe this truncation with the OC instruction. In these plotters,
the OC instruction returns decimal parameters instead of integer
parameters when scaling is in effect. ■
When scaling is on, any fractional portion of a parameter is used.
A PA command without parameters sets absolute plotting mode for PU
and PD commands with parameters.
When parameters are included with a PA command, both coordinates
of an X,Y coordinate pair must be given. An odd number of parameters
CONTROLLING THE PEN AND PLOTTING
will set an error condition but all X,Y pairs which precede the un­
matched parameter will be plotted.
The X-coordinate specifies, in either plotter units or user units, the
absolute X-location to which the pen will move. The Y-coordinate speci­
fies, in either plotter units or user units, the absolute Y-location to
which the pen will move. If scaling is on, coordinates are in user units.
If scaling is off, coordinates are in plotter units.
The mnemonics PU and PD can be included ahead of, between, or after
X,Y coordinate pairs. PU lifts the pen; PD lowers the pen.
Any number of coordinate pairs, as well as PU or PD mnemonics, can
be listed after a PA instruction. (This is limited only by the ability of
the controller to output without a line feed character which is an instruc­
tion terminator.) The pen will move to each point in the order given.
Commas, spaces, or a sign are required between numeric parameters
and are optional after two-letter mnemonics. The last entry is followed
by the terminator. In the following examples, commas are used to show
optional and required separators. Optional commas or spaces which
can be used between each letter of the mnemonics are not shown. The
semicolon is used to indicate the terminator.
P A,PD,Xi
)
Yi,PU,X
2
,Y2
)
PD,X3,Y
3>
;
I ' 1 1 1 1 1 OPTIONAL
PU,Xi
(
Yi
)
PD,X2
>
Y2,X
3)
Y3,PU;
I ' ' 1 OPTIONAL
PD,Xi,Yi,X
2
,Y2,X3,Y3,;
• 1 OPTIONAL
If no pen control parameter is given, the pen will assume the pen state
(up or down) of the previous statement. The PU or PD mnemonics can
also be substituted for the PA (or PR) mnemonic. This is equivalent to
having PU; or PD; preceding the PA or PR instruction. Therefore, P U
and PD with parameters are interpreted to be in place of PA or PR,
depending upon which mnemonic, PA or PR, was last specified.
PA is specified by any of the following:
• power-up,
• execution of an IN command,
CONTROLLING THE PEN AND PLOTTING 3-5