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E Series DAQ Accuracy Speciﬁcations

Relative Accuracy

Relative accuracy is the speciﬁcation that compares the difference

between two or more measurements. It indicates the degree to

which two or more measurements can be distinguished from each

other. The two major contributors to relative accuracy are the

resolution of the device’s analog-to-digital Converter (ADC) and the

system noise. The accuracy tables show both single-point and

averaged relative accuracy, which include both ADC resolution and

system noise effects. Averaging will improve your relative accuracy

for DC measurements.

As an example, assume you are monitoring a voltage once per

second using the ±10 V range on the PCI-MIO-16XE-50 and

averaging 100 points for each measurement. Using the accuracy

table on page 255 (reprinted below for your convenience), we ﬁnd:

Averaged Relative Accuracy = 60.3 µV

This means that a measurement taken at time t

would have to be

60.3 µV greater or less than the measurement taken at time t

order to detect a difference in the input voltage. Relative accuracy

does not depend on DAQ device calibration.

Detailed Speciﬁcations

The pages starting at page 266 contain detailed speciﬁcations for all

National Instruments E Series multifunction devices. Devices can be

identiﬁed by their family number. For instance, if you want to

determine the common-mode rejection ratio (CMRR) in the 10 V

range for the PCI-6052E in unipolar range, you would look at the 16-bit

E Series Multifunction DAQ speciﬁcation on page 272. For the 10 V

range, the CMRR speciﬁcation for the NI 6052E devices is 97 dB.

235

National Instruments • Tel: (800) 433-3488 • Fax: (512) 683-9300 • [email protected] • ni.com

E Series DAQ Accuracy Speciﬁcations

Measurements

Table 1. NI 601xE Analog Input Accuracy Speciﬁcations

Absolute Accuracy Relative Accuracy

Nominal % of Reading Offset Noise + Quantization (µV) Temp Absolute Accuracy Resolution (µV)

Range (V) 24 Hrs 90 Days 1 Year (µV) Single Pt. Averaged Drift (%/°C) at Full Scale (mV) Single Pt. Averaged

±10 0.0058% 0.0078% 0.0100% 397.2 526.4 45.8 0.0002 1.443 602.7 60.3

±5 0.0208% 0.0228% 0.0250% 200.6 263.2 22.9 0.0007 1.474 301.4 30.1

±1 0.0208% 0.0228% 0.0250% 43.3 52.6 4.6 0.0007 0.298 60.3 6.0

±0.1 0.0408% 0.0428% 0.0450% 7.9 8.4 0.7 0.0012 0.054 9.6 1.0

0 to 10 0.0058% 0.0078% 0.0100% 244.6 263.2 22.9 0.0002 1.268 301.4 30.1

0 to 5 0.0208% 0.0228% 0.0250% 124.3 131.6 11.4 0.0007 1.386 150.7 15.1

0 to 1 0.0208% 0.0228% 0.0250% 28.1 26.3 2.3 0.0007 0.280 30.1 3.0

0 to 0.1 0.0408% 0.0428% 0.0450% 6.4 7.0 0.6 0.0012 0.052 8.4 0.8

±10 0.0075% 0.0095% 0.0117% 815.4 1029.1 91.6 0.0005 2.077 1205.4 120.5

±5 0.0225% 0.0245% 0.0267% 409.7 514.6 45.8 0.0010 1.791 602.7 60.3

±1 0.0225% 0.0245% 0.0267% 85.1 102.9 9.2 0.0010 0.361 120.5 12.1

±0.1 0.0425% 0.0445% 0.0467% 12.1 12.2 1.1 0.0015 0.060 14.5 1.4

0 to 10 0.0075% 0.0095% 0.0117% 591.2 514.6 45.8 0.0005 1.807 602.7 60.3

0 to 5 0.0225% 0.0245% 0.0267% 297.6 257.3 22.9 0.0010 1.656 301.4 30.1

0 to 1 0.0225% 0.0245% 0.0267% 62.7 51.5 4.6 0.0010 0.334 60.3 6.0

0 to 0.1 0.0425% 0.0445% 0.0467% 9.9 8.0 0.7 0.0015 0.057 9.6 1.0

Note: Accuracies are valid for measurements following an internal E Series Calibration. Averaged numbers assume dithering and averaging of 100 single-channel readings. Measurement accuracies are listed for

operational temperatures within ±1 °C of internal calibration temperature and ±10 °C of external or factory-calibration temperature. One-year calibration interval recommended. The Absolute Accuracy at Full Scale

calculations were performed for a maximum range input voltage (for example, 10 V for the ±10 V range) after one year, assuming 100 pt averaging of data. See Overview on page 234 for an example calculation of this type.

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