Digitizing With; Manual Method - HP 7470A Interfacing And Programming Manual

The timing of output depends on the plotter's interface (HP-IB, HP—IL,
or RS-232-C).Refer to A Brief Word about Plotter Output in Chapter 7
for more information.
The pen position and status are output to the computer as integers in
ASCII in the form:
X,Y,P [TERM]
where X is the X-coordinate of the digitized point in plotter units,
Y is the Y—coordinate of the digitized point in plotter units,
P is the pen status when the point was entered (0 = pen
up, 1 = pen down), and
[TERM] is the output terminator for your system (refer to Chap­
ter 7).
The ranges of the X- and Y—coordinates a re the mechanical limits of the
plotter as determined by the setting of the paper switch.
Upon receipt of the OD command by the plotter, bit position 2 of the
output status byte is cleared.
Digitizing with the 7470
When using the plotter as a digitizer, it is important to ascertain that a
point has been entered before an attempt is made to retrieve that point
using the OD command. There are three methods for doing this.
Manual Method
The first method, which might be called the manual method, is easiest
to understand. It is not efficient in applications where many points will
be entered, or in an RS-232—C e nvironment where the mainframe is not
adjacent to the plotter or where human intervention in program execu­
tion is not possible. The steps in this method are as follows:
1. In a program, send a DP command to the plotter. Follow the DP
command immediately with a statement that will cause the program
to display or print a message prompting you to enter a point. Follow
the prompt with a statement that will cause the program to pause
until instructed to continue. The BASIC statement PAUSE will
accomplish this.
2. Move the digitizing sight (pen) to the point to be entered, using front­
panel buttons. Final positioning should be done with the sight (pen)
down.
3. Press ENTER on the plotter's front panel. Now resume running of the
program. This is done on HP desktop computers by pressing the key
marked CONTINUE or CONT.
6-4 DIGITIZING