ADLINK PXI-2022 - Manual (Page 28)

20 Signal Connections
3.2 Analog Input Signal Connection
The PXI-2020/2022 provides 8/16 differential analog input chan-
nels. The analog signal can be converted to digital values by the
A/D converter. To avoid ground loops and obtain more accurate
measurements from the A/D conversion, it is quite important to
understand the signal source type and how to connect the analog
input signals.
3.2.1 Types of Signal Sources
Ground-Referenced Signal Sources
A ground-referenced signal means it is connected in some way to
the building system. That is, the signal source is already con-
nected to a common ground point with respect to the PXI-2020/
2022, assuming that the computer is plugged into the same power
system. Non- isolated outputs of instruments and devices that plug
into the buildings power system are ground-referenced signal
sources.
Floating Signal Sources
A floating signal source means it is not connected in any way to
the buildings ground system. A device with an isolated output is a
floating signal source, such as optical isolator outputs, transformer
outputs, and thermocouples.