HP 3456A Operating And Service Manual page 304

Appendix 0
Example. Progrem B: High Speed Data
Acquisition
This example, like Example Program 7, uses the 3456A
internal memory and Program Memory Execution
Complete interrupt capabilities to achieve high speed
data acquisition. When less than approximately 350
readings are required, the highest instrument reading
rate may be obtained by using the internal memory. Ex­
ample Program 9 discusses high speed techniques when
more than 350 readings are required. Enter program
lines in Figure 12.
Program 8 Explanation
Line 0: This statement allows you to enter the desired
number of readings. After you press (RUN),
type in a number between 100 and 340 and
press (CONTINUE).
Line I : The computer will go to "DATA" upon receiv­
ing an interrupt.
Line 2: An array is dimensioned to hold N readings.
Line 3 : The 3456A is set for high speed data acquisi­
tion:
DO . . . . . . . . . . . . . . . . . . . . . . . . . . . Display Off
. . . . . . . . . . . . . . . . . . . . . . . Auto Zero Off
ZO
.
R4 . . . A preset range is faster than auto range
since the instrument does not have to determine
the proper range .
. DISTI . . . . . 01 is the shortest integration time
Also the 3456A stores the readings internally,
N readings per trigger, single trigger, sets the
SRQ mask for Program Memory Execution
Complete, and executes the 3456A stored pro­
gram codes.
Line 4: Computer enables the interrupt. K is initialized
to O. Flag I is set to I .
0-10
Rev A
0: E'rot " Hu.',ber of RE''ld ln",s'? ( 1 00Ul<340 ) '' , tl
OtH
1 : 7 , ' " D A T A "
2 : d i (ll vCt n
1
0 1
3 : w r t 722, ' " L I DOZOR4 .
5: K+bV : �J 'l u
4 : E' l r 7 ; O�K ; � f ",
6: 1 f not f l
I f n <;t l i d s p
'J
7 :
I ; dsp MEASIJREf1EtnS CO�lPLETED··
..
8 :
E'nd
9 :
" D A T A " :
r d s ( 7 2 2 ) �S ; c f ", 1
1 0 : ·
w r t 722 , -N , '"STRRER'" j l'xd
1 1 : f o r J = 1
t o tl: red 722, V[ J ] ; dsp
1 2 :
i rE't
-i l � 152
Figure 12. Example Program 8.
I
Line 5: If flag I is I , the computer executes this count
loop. Flag will be cleared in the interrupt
routine.
Line 6: If flag 1 is 0, the quoted text is displayed.
Line The main program is terminated.
7:
Line 8: The interrupt routine is labeled.
Line 9: The status Byte is read. Flag I is cleared to O.
Line 10: The 3456A recalls the stored data.
Line 1 1 : The computer reads and displays the data.
Line 12: Execution is returned to the main program.
hample Program 9: High Speed Data
Acquisition and Transfar - Unpacking Program
The normal method of sending measurement data re­
quires a total of 14 bytes to be sent for each reading.
This is a constraint when trying to take and transfer
readings at a high speed since much of the 3456A's pro­
cessing time is tied up with transmitting the informa­
tion. A faster method of transferring the data is to use
the 3456A's packed data mode. This mode condenses
the number of bytes required from 14 to 4.
After the packed data has been read into the desktop
computer, the data must be unpacked to put the infor­
mation into a useable form. The desktop computer fur-
ther increases the data transfer rate by accepting the
packed data into a high speed read/write memory com­
partment called a buffer. The contents of the 4 bytes us-
ed for the packed data mode are shown in Figure 1 3 .
Enter program lines in Figure 14.
The decimal point in the Packed Formal is
implied to the Overrange Digit's l e f t.
" , 110
ST I R S l
" S THT3QHSM002i(l ..
200i JI'lP 0
<4
V( J ] : wa l t 200
Model 3456A
NOTE
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