DAQ DAQCard-1200 User Manual page 35

Chapter 3 Connecting the Signals
+
Floating
Signal
V
s
Source
–
Front I/O Connector
DAQCard-1200 User Manual
1 ACH 0
2 ACH 1
3 ACH 2
8 ACH 7
9 AISENSE/AIGND
11 AGND
DAQCard-1200 in RSE Configuration
Figure 3-5. Single-Ended Input Connections for Floating Signal Sources
Single-Ended Connections for Grounded Signal Sources (NRSE Input
Mode)
If you measure a grounded signal source with a single-ended configuration,
you must configure the DAQCard-1200 in the NRSE input configuration.
The signal is connected to the positive input of the DAQCard-1200
instrumentation amplifier, and the signal local ground reference is
connected to the negative input of the DAQCard-1200 instrumentation
amplifier. Therefore, you must connect the ground point of the signal to the
AISENSE/AIGND pin. Any potential difference between the
DAQCard-1200 ground and the signal ground appears as a common-mode
signal at both the positive and negative inputs of the instrumentation
amplifier and is therefore rejected by the amplifier. NRSE input mode must
be used in place of the RSE input mode to prevent any difference in ground
potentials from appearing as an error in the measured voltage.
Figure 3-6 shows how to connect a grounded signal source to a
DAQCard-1200 configured in the NRSE configuration. For configuration
instructions, refer to the
Installing and Configuring the
+
–
Configuring Analog Input
DAQCard-1200.
3-12
+
Measured
V
m
Voltage
–
section of Chapter 2,
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