JYTEK NuDAQ PCI-69222, User Manual

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20 Hardware Information
2.3 Analog Input Signal Connection
The PCI-69222 provides up to 16 single-ended or 8 differential
analog input channels, while the PCI-69223 offers up to 32 single-
ended or 16 differential analog input channels. You can fill the
Channel Gain Queue to get the desired input signal type combina -
tion. The analog signal can be converted to digital value by the
A/D converter. To avoid ground loops and obtain a more accurate
measurement from the A/D conversion, it is important to under -
stand the type of signal source and how to choose the analog
input modes: Referenced Single-Ended (RSE), Non-Referenced
Single-Ended (NRSE), and Differential Input (DIFF).
Types of Signal Sources
Floating Signal Sources
A floating signal source means it is not connected in any way to
the building’s ground system. A device with an isolated output
is a floating signal source. This includes optical isolator out -
puts, transformer outputs, and thermocouples.
Ground-Referenced Signal Sources
A ground-referenced signal means it is connected in some way
to the building’s ground system. That is, the signal source is
already connected to a common ground point with respect to
the PCI-69222/PCI-69223, assuming that the computer is
plugged into the same power system. Non-isolated outputs of
instruments and devices that plug into the building’s power sys -
tems are ground-referenced signal sources.