SCC-68 User Guide
26
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The difference in potential between the ground of the signal source and
AI GND causes an error when measuring the signal. The amount of this
error depends on several factors including the length of the cable
connecting the DAQ device to the SCC-68 and the amount of current being
drawn by the SCC-68 from the DAQ 5V power supply.
Floating Signal Sources
Floating signals can be measured in NRSE mode with AI SENSE and
AI GND connected together with certain limitations. This configuration
can have implications depending on the bias resistor requirements of the
signal source. Refer to the
M Series User Manual
or the
E Series Help
for
more information regarding floating source bias requirements.
Figure 17.
Floating Signal Connected in NRSE Mode
Ground-Referenced Single Ended (RSE)
Refer to the RSE connection considerations described in the
M Series User
Manual
or the
E Series Help
. The following cases should also be noted.
Grounded Signal Sources
This configuration is not recommended as described in the
M Series User
Manual
or the
E Series Help
.
Floating Signal Sources
Connecting a floating signal source in RSE mode is not recommended.
When measuring floating signals with the SCC-68 configured for SCC
modules, use the NRSE measurement configuration.
Floating
Signal
AI GND (Pin 67)
AI
AI SENSE (Pin 62)
SCC-68
DAQ Device
NRSE Mode
+
–
+
–
