Advantech iDAQ-871 handleiding
Handleiding
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17 iDAQ-871_873 User Manual
Chapter 3 Function Details
3.1.2.2 Offset Nulling
In fact, output of the bridge may not be 0 V even when not loaded. This is because
slight variations in resistance among the bridge arms generate nonzero offset volt-
age. Offset nulling performs software compensation for this offset voltage.
The software will first measure the bridge output when not loaded and stored it as an
initial value. Then this initial value will be subtracted from the reading before scaling
when measuring under load.
3.1.2.3 Shunt Calibration
In shunt calibration, load is simulated by shunting a shunt calibration resistor (R
SC
)
inside the device to R
B2
of the bridge, which results in equivalent resistance change
on that arm. A switch inside the device controls whether to connect R
SC
or not.
Because values of all resistors are known, and the resistance change on the shunt-
ing arm is also known, the theoretical value of this simulated load can therefore be
calculated. Then the bridge output when shunting is measured, and the ratio between
the theoretical value and the measured value is stored and used when scaling the
reading.
3.2 Strain Gauge Sensor Configurations
This section describes the supported strain gauge sensor configurations.
3.2.1 Quarter-Bridge Configuration
This section provides information for the quarter-bridge strain gauge sensor configu-
ration. This configuration measures either axial or bending strain. Figure 3.5 shows
how to position the strain gauge sensor in both axial and bending configurations.
Refer to 2.3.1 Quarter-Bridge Input Signal Connection for detailed signal wiring of
this configuration.
Figure 3.5 Quarter-bridge configuration measuring axial and bending strain
The quarter-bridge configuration has the following characteristics:
A single active strain gauge sensor R
B1
is mounted in the principal direction of
axial or bending strain.
Sensitive to both axial and bending strain.
A quarter-bridge completion resistor R
QB
and two half-bridge completion resis-
tors R
HB
are required. They are provided by the device.
Both a shunt calibration resistor R
SC
and a switch are provided by the device.
Sensitivity ≈ 0.5 μV/V per με, for GF = 2.0.
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Productinformatie
| Merk | Advantech |
| Model | iDAQ-871 |
| Categorie | Niet gecategoriseerd |
| Taal | Nederlands |
| Grootte | 5398 MB |
