HP 7470A Interfacing And Programming Manual page 121

The program lines which plot the two lower lines and the correspond­
ing legend lines are:
260 PRINT "SP1;LT3,B;F'FI1 2'
12 2?F'U"
270 PRINT "PDS 27 7 2? 9 1
'5
J
290 PRINT "SF'2;L.T8,8;F'F11,45'
E
n ;
9 4
280 PRINT "PH?.8,185 PDS.n 155 PU
,PD;PPz,5o,3,52,4,53,5,52"
300 PRINT"Pn5,51,?,55,s,5 ,9,5E,10,S8,11,58,12,EOPU"
310 PRINT "PH10.1,165 PU11.5,1s5 PU"
The third line is plotted from data read by the program at execution
time using a FOR...NEXT loop and a READ statement. This technique
would be used to plot a graph that will be replotted often with new
data. If the necessary file statements were added, the data could be on
a tape or disk file instead of in a DATA statement as shown here. The
line type for this line is the default solid line, reverted to by the LT'
command with no parameters. Since we are using variables as plot
parameters, you need to be sure they are sent to the plotter with a space
between numeric variables. Computers often send a leading and/or
trailing blank or allow for a sign space before numeric variables. The
7470will treat a blank, comma, or sign as a separator between numeric
parameters. Know your computer before sending variables with plot
commands. As with the two previously drawn lines, after the line is
plotted, the corresponding line is placed in the legend.
The loop to plot this third line and the statements to place a line in the
legend are:
320 PRINT "LT"
330 FUR x=1 TO 12
340 RERD Y
350 PRINT "PH";X;Y;"PD"
350 NEXT x
370 PRINT "PUB,165PD?.1,1E5PU"
410 DHTH 55,80,83,52,59,s4,5o,4s,47,43,53,5s
The last line is drawn using a subroutine. The subroutine is designed to
read data that have been stored with a third value for pen control. This
third value controls a branch to two different plot statements, one with
the pen up and the other with the pen down. In this program, a zero as
a pen control parameter results in a pen up move, a 1 causes plotting
with the pen down, and 3 signifies the end of the data. The legend line
is drawn at the end of the subroutine, completing the graph.
PUTTING THE COMMANDS TO WORK 8-7