Measuring Floating Signals In Single-Ended Input Mode - National Instruments BNC-2090A User Manual

Chapter 2 Connecting Signals
BNC-2090A User Manual
referenced single-ended (RSE) modes, refer to the E Series User
Manual or the M Series User Manual.
4. Configure your software to measure this channel in RSE or NRSE
mode.
Figure 2-3 shows how single-ended AI signals are routed to the DAQ
device.
AI 0
SE
DIFF
AI 8
Figure 2-3. Analog Input Single-Ended Mode
Moving the RSE/NRSE switch to RSE, connects the BNC shields to
AI GND. Moving the RSE/NRSE switch to NRSE connects the BNC
shields to AI SENSE.
Measuring Floating Signals in Single-Ended Input
Mode
A floating signal source is a signal source that is not connected in any way
to the building ground system, but has an isolated ground-reference point.
If an instrument or device has an isolated output, that instrument or device
falls into the floating signal source category. Some examples of floating
signal sources are thermocouples, transformers, battery-powered devices,
optical isolators, and isolation amplifiers. The ground reference of a
floating source must be tied to the ground of the DAQ device to establish a
local or on-device reference for the signal.
When measuring floating signal sources, configure the DAQ device to
supply a ground reference by placing the device in referenced single-ended
(RSE) mode. This mode ties the negative input of the DAQ device
instrumentation amplifier and the BNC shield to the analog ground.
BNC-2090A
RSE
NRSE
RSE/NRSE
Switch
2-4
Cable DAQ Device
AI 0
AI GND
AI SENSE
AI 8
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