Keysight Technologies DAQ970A Technical Overview page 10

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Example 3: Thermocouple measurement accuracy
Calculating the total thermocouple reading error is easy with
the DAQ970A—just add the listed measurement accuracy to the
accuracy of your transducer. Switching, conversion, and reference
junction errors are already included in the measurement
specification.
For this example, assume a J-type thermocouple input reading 150°C.
From the following page, total error is:
Thermocouple probe accuracy + 1.0°C
The probe vendor specifies accuracy of 1.1°C
or 0.4%, whichever is greater.
Total error is then:
1.0ºC + 1.1ºC = 2.1ºC total, or 1.4%
DAQ970A Accuracy Specifications ±(% of reading + % of range)
Specifications: DC Voltage and resistance. Automatic calibration (ACAL) capable.
3
Range
Accuracy ± (% of reading + % of range)
2
DC voltage
100 mV
1 V
10 V
100 V
300 V
Resistance 2, 7
100 Ω
1 KΩ
10 KΩ
100 KΩ
1 MΩ
10 MΩ
100 MΩ
1000 MΩ
1. Specifications are for 60-minute warm-up, integration setting of 10 or 100 NPLC, auto-zero on, AC slow filter. ACAL run within the last 2 days & 901 module connectivity.
2. These specifications include offset characteristics contributed by the 901 Module & backplane (which adds DCV + 2 uV, 4-wire ohms + 2 mΩ)
3. 20% over range on all ranges, except 300 VDC, 300 VAC, 1 ADC, 1 AAC, and diode test have 0%.
4. Relative to calibration standards. 24 hrs spec only applicable when calibrated with the same DAQM901 module that is being used to verify spec.
5. Add this for each °C outside the last ACAL ± 5 °C.
6. Add this for each °C outside the last external standards calibration ± 5 °C.
7. Specifications are for 4-wire ohms function or 2-wire ohms using math null for offset. Without math null, add 2 Ω additional error in 2-wire ohms function. The 100M and 1G
ohm ranges are 2-wire only. See the manual for low power ohms specification and measurement currents.
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24 Hour 4 90 Days
Tacal ± 1 °C Tacal ± 5 °C
1
0.0030 + 0.0050 0.0040 + 0.0060
0.0015 + 0.0006 0.0025 + 0.0006
0.0010 + 0.0003 0.0021 + 0.0004
0.0020 + 0.0006 0.0035 + 0.0006
0.0020 + 0.0020 0.0035 + 0.0020
0.0030 + 0.0050 0.0050 + 0.0060
0.0020 + 0.0007 0.0030 + 0.0007
0.0020 + 0.0005 0.0030 + 0.0005
0.0020 + 0.0005 0.0030 + 0.0005
0.0020 + 0.0005 0.0060 + 0.0005
0.010 + 0.001 0.020 + 0.001
0.100 + 0.001 0.250 + 0.001
2.000 + 0.001 2.500 + 0.001
Allice Messtechnik GmbH
Example 4: acV accuracy
The acV function measures the true RMS value of the input
waveform, regardless of waveshape. Listed accuracies assume a
sinewave input. To adjust accuracies for non-sinusoids, use the
listed crest factor adder.
For this example, assume a ± 1 V square wave input with
50% duty cycle and a 1 kHz frequency.
Accuracy for 1 V, 1 kHz sinusoid is:
0.05% reading + 0.02% range = 0.7 mV or 0.07%
1 Year 2 year
Tacal ± 5 °C Tacal ± 5 °C
0.0050 + 0.0060 0.0065 + 0.0060
0.0035 + 0.0006 0.0050 + 0.0006
0.0030 + 0.0004 0.0045 + 0.0004
0.0040 + 0.0006 0.0055 + 0.0006
0.0040 + 0.0020 0.0055 + 0.0020
0.0060 + 0.0060 0.0070+ 0.0060
0.0040 + 0.0007 0.0050 + 0.0007
0.0040 + 0.0005 0.0050 + 0.0005
0.0040 + 0.0005 0.0050 + 0.0005
0.0070 + 0.0005 0.0080 + 0.0005
0.025 + 0.001 0.030 + 0.001
0.350 + 0.001 0.400 + 0.001
3.500 + 0.001 4.000 + 0.001
Non ACAL With ACAL
Temperature Temperature
5
Coefficient /°C Coefficient /°C
0.0005 + 0.0005 0.0002 + 0.0005
0.0005 + 0.0001 0.0002 + 0.0001
0.0005 + 0.0001 0.0002 + 0.0001
0.0005 + 0.0001 0.0002 + 0.0001
0.0005 + 0.0001 0.0002 + 0.0001
0.0006 + 0.0005 0.0002 + 0.0005
0.0006 + 0.0001 0.0002 + 0.0001
0.0006 + 0.0001 0.0002 + 0.0001
0.0006 + 0.0001 0.0002 + 0.0001
0.0010 + 0.0002 0.0002 + 0.0002
0.0030 + 0.0004 0.0030 + 0.0004
0.1000 + 0.0001 0.0100 + 0.0001
1.0000 + 0.0001 0.1000 + 0.0001
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