Table of Contents
Section III
3-24. The 3485A may be programmed to take bursts of
readings across the same
channels,
store each burst then
output all readings. The number of channels scanned must
be divisible into the Storage Limit an integral number of
times. For example,
2
bursts of 10 channels with Storage
Limit
=
20. Table 3-7 illustrates the different
combinations.
A timing
example is
shown
in
Figure 3-13 with a printout
in Figure
3-14.
Table 3-7.
3485A/Data Storage Operation for Bursts of Readings.
3485A
Last Channel
Storage Limit
Number
Setting
Setting
of Bursts
5
10
2
5
20
4
5
30
6
5
40
8
5
50
10
10
20
2
10
30
3
10
40
4
10
50
5
25
50
2
2
10
5
2
20
10
2
30
15
2
40
20
2
50
25
3
30
10
4
40
10
I H U R N A L T l l l G G U l f W I T H I N S C A f O I E ; : . R l - - - - - - - - - - - - -
l.J1•IURST
LJ2ndBURST
I
OCHA NNELS
INO
.
JTHROUGHN0.
10)
!OCHANNHS
(NQ
.
lTH AOUG
HN0.
101
f--OUTPUT
-
"' " 1
n
I
~-------~
~------~·
STORAGEflAG
(fRO
MD VM
)
lflrl0···
PlllliTEAHOLO·O HITOOVMI
_ _ _ _ _ ___,11.flf-··
INl'UT
CYCLE
,
21
URSTSOF
10 CHANNEl$
-~ "'~"':GE~l~'"'-'-'
· ·
" -20
·
_ _
}GROUNDED
Figure 3-13. Burst Operation.
OUTl'UT
CY
ClE
2011f AOINGS
Data Storage may be used to store bursts of scanned readings from
the 3485A Scanning Unit. In this case, two bursts of 10 channels are
stored. Separate Program Initiate commands are given to the scanner
to start the scanning sequence. Ready indicates when the scanner
may be given its next Program Initiate. The Storage Limit is set to
"20" to input and output 20 readings.
3-8
2ND
BURST
OF
25 CHANNELS
PROGRAM
INITIATE - -
IST BURST
Of
25
CHANNELS
PROGRAM
INITIATE
- -
llllOA-1-1525
5020604328
4 9 2 0 6 0
4
5 0 9
4820604292
4
7 2
0
6 0 4 0 5
8
4
6
2
0
3 0 5
6 4 9
4 5 2 0 2 0 4 5.
8
4410204519
4310204353
4210604132
4110701062
4010701753
3910701713
3810301673
3710301741
3610301658
3 5 1 0 7
0
1 7
7
1
3400701679
3300700679
3200300319
3100305199
3000704653
2900701459
2800704120
2 1
0
0 1
0 1 5
0 0
2600301010
2520601
510
2420601512
2320601621
2220601482
2120201440
2020205572
1910205032
1810205160
1 7 1 0 6 0 4 1 7 1
1
6
1 0
6 0 5 1 7
0
1510605060
1410605681
I
3
1
0
2
0 5 4
9
0
12
10204180
1110204409
1 0 1
0
6 0 I 0 4 0
0900601190
0800604070
0700601180
0600201072
0500201632
0400201392
0300601271
0200600033
0100601423
Figure 3-14. Burst Printout.
Model 1 l l 80A
The print-out on a 2070A is shown for scanning two bursts of 25
channels then outputting all 50 readings (Storage Limit = 50; Last
Channel= 25). Note how the 10's Channel l.D. helps identify each
burst.
3-25. SAMPLE-ANO-HOLD IMPROVES DIGITIZING.
3-26.
The successive approximation technique used for
A/D
conversion
in the 3480 is limited
in
its ability to
accurately digitize a changing
input
voltage. This limit
is
equal to 10% of the full-scale voltage range/s or on the 10 V
range, 1 V /s. This translates to a 0.018
Hz
sine wave
digitized to
±
0.01
%
accuracy.
3-27. Sample-and-hold may be added to the
3480
main
frame as shown in Figure 3-15. Sample-and-hold takes the
changing
input signal conditioned by the plug-in and holds
it just prior to A/D conversion. The A/D converter,
therefore,
looks at a de level which represents the signal
level at the time of the sample as shown in Figure 3-16.
IJ
]
J
:
J
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