338 Appendix D Optimizing Throughout and Reading Rate
Still Faster A considerable increase in throughput can be had if you use TRANSFER
statements instead of OUTPUT and ENTER statements. Further, the juxtaposition
of some commands improve the measurement speed. Notably, the sequence for
DELAY and ACBAND when working with ACV can make a large difference in
execution speed. The proper sequence is:
DELAY <#>;ACBAND <#,#>;ACV <range>.
If you want to change the default settling times when you change a function,
always change the DELAY command first. It is also faster in many cases to remain
on one integration time rather than change. For example, to get 6 1/2 digits
resolution, the 3458A can be set to APER 10E-5 (100 µs), where it can take almost
10,000 readings per second. If measurement calls for only a few measurements
with this resolution and a greater number with less resolution, it still may be faster
to leave the integration time at 100 µs and take all the measurements there. It takes
about 6 to 10 ms for the 3458A to change integration time. At about 10,000
readings per second, the 3458A can take one hundred 6 1/2 digit readings in that
time.
This last program uses transfers and the proper command sequence to achieve the
greatest possible throughput for the benchmark program.
Execution time = .360 s
Program Memory Download Time = .05 s
Reading Transfer time = .05 s
10 OPTION BASE 1
20 DIM Command$[1000] BUFFER
30 DIMA$[100],B$[100],C$[100],D$[100],E$(100],
F$[100],G$[100],H$[100],I$[100],Set_up$[100]
40 INTEGER I,M
50 REAL Readings(37) BUFFER
60 ASSIGN @Dmm TO 722
70 ASSIGN @Buf_1 TO BUFFER Command$
80 ASSIGN @Buf_2 TO BUFFER Readings(*)
90 CLEAR 722
100 OUTPUT @Dmm;"RESET"
110 Set_up$="PRESET;MFORMAT SREAL;DEFEAT ON;APER 100E-6;DISP OFF,TESTING"
120 B$="SUB Try;MEM FIFO;DELAY O;OHM,1E4;NRDGS 15;TRIG SGL;"
130 C$="OHM,1E5;NRDGS 8;TRIG SGL;"
140 D$="DELAY -1;OHMF,1E3;NRDGS 2;TRIG SGL;"
150 E$="DELAY .1;ACBAND 5O;ACV 250;NRDGS 1;TRIG SGL;
160 F$="DELAY .01;ACBAND 25000;ACV,10;TRIG SGL;"
170 G$="DELAY 0;DCV 10;NRDGS 6;TRIG SGL;"
180 H$="DELAY .01;ACBAND 5000;ACV 10;NRDGS 1; TRIG SGL;"
190 I$="DELAY 0;DCV 10;NRDGS 3;TRIG SGL;SUBEND"
200 Command$=B$&C$&D$&E$&F$&G$&H$&I$
210 Dnload:! Transfer commands to dmm
220 Dnld_time=TIMEDATE
230 OUTPUT @Dmm;Set_up$
240 TRANSFER @Buf_1 TO @Dmm
250 Dnld_time=TIMEDATE-Dnld_time
260 Execute: ! Dmm Execution time
270 Exe_time=TIMEDATE
280 OUTPUT @Dmm;"CALL Try"
290 Exe_time=TIMEDATE-Exe_time
300 Read:! Transfer the readings to the Computer
310 Tns_time=TIMEDATE
320 TRANSFER @Dmm TO @Buf_2
330 Tns_time=TIMEDATE-Tns_time
340 PRINT "DOWN LOAD TIME =";Dnld_time
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