National Instruments VirtualBench - Page 33

NI VirtualBench Calibration Procedure | © National Instruments | 33
• Probe Attenuation = 1x
• Vertical Range = 20
• Vertical Offset = 0
Note
Configure the oscilloscope calibrator for high impedance loads.
5. Set the oscilloscope calibrator DC voltage output to -90% of the range, or -18 V.
6. Wait at least 5 seconds for the oscilloscope calibrator to settle.
7. Call
MSO Run.
8. Call
MSO Read. Calculate and record the average analog waveform. Save this value as
V
meas_neg
.
9. Set the oscilloscope calibrator DC voltage output to +90% of the range, or +18 V.
10. Wait at least 5 seconds for the oscilloscope calibrator to settle.
11. Call
MSO Run.
12. Call MSO Read. Calculate and record the average analog waveform. Save this value as
V
meas_pos
.
13. Call
MSO Stop.
14. Calculate the gain error as follows:
Where V
pos
and V
neg
are listed in Table 14.
Verify that this calculation falls within the limits in Table 14.
Table 14. Oscilloscope Gain Verification Limits
Range (V) V
pos
(V) V
neg
(V)
1 Year Limits (%) 24 Hour Limits (%)
Lower Upper Lower Upper
20 18 -18 -2 2 -0.8 0.8
10 9 -9 -2 2 -0.8 0.8
5 4.5 -4.5 -2 2 -0.8 0.8
2 1.8 -1.8 -2 2 -0.8 0.8
1 0.9 -0.9 -2 2 -0.8 0.8
0.5 0.45 -0.45 -2 2 -0.9 0.9
0.2 0.18 -0.18 -2 2 -0.9 0.9
0.1 0.09 -0.09 -2 2 -1 1
V
meas_pos
V
meas_neg
–()
V
pos
V
neg
–()
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