NI WSN-3214, Руководство пользователя и технические характеристики

Страница: 41 / 53

© National Instruments 41 NI WSN-3214 User Guide and Specifications
Analog Input Characteristics
Number of channels ...............................................4 analog input channels
Sampling mode ......................................................Scanned
ADC resolution ......................................................20 bits
Type of ADC..........................................................Oversampled converter
DNL .......................................................................No missing codes guaranteed
Modes (configurable per channel) .........................Full-bridge, half-bridge, quarter-bridge
Bridge completion
Quarter-bridge and half-bridge ......................Internal
Bridge resistance
Full-bridge .....................................................350–1,000
Ω
Half-bridge.....................................................350–1,000
Ω
Quarter-bridge................................................350, 1,000
Ω
Powerline filtering modes ......................................50 Hz, 60 Hz, 50/60 Hz, none
Overvoltage protection...........................................±30 VDC
Input range .............................................................±20 mV/V
Table 3. Accuracy
Measurement
Conditions *
Percent of
Reading
(Gain Error)
Percent of Range †+
(Offset Error)
Full-Bridge Half-Bridge Quarter-Bridge
Typical, 25 °C, ±5 °C ±0.1% ±0.005%
(1
μ
V/V)
±0.7%
(140
μ
V/V)
±0.5%
(100 μ
V/V)
Maximum, –40 to 70 °C ±0.45% ±0.03
(6
μ
V/V)
±1%
(200
μ
V/V)
±1%
(200
μ
V/V)
*
After using shunt calibration for quarter-bridge and using remote sensing for full/half-bridge to remove errors
from lead wire resistance
†
Range equals 20 mV/V.
+
Before offset null. The offset error can be removed for current temperature conditions by using offset null. After
doing offset null, the offset error of the measurement is determined by the temperature drifts over the expected
temperature range. For example, if you perform an offset null for a half-bridge measurement at a temperature of
25
°
C and the expected temperature variation is 20 °C, then the typical offset error for the measurement is as
follows:
offset error
HB
= (0.06% of range)
0.6
uV
V
-------
1
°
C
------
20
°
C
× ×
12
uV
V
-------
=