ADLINK DAQe-2214 - Manual (Page 38)

26 Signal Connections
3.2 Analog Input Signal Connection
The DAQ-/DAQe-2213/2214 card provides up to 16 single-ended
or eight differential analog input channels. You can fill the Channel
Gain Queue to get desired combination of the input signal types.
The analog signal can be converted to digital values by the A/D
converter. To avoid ground loops and get more accurate measure-
ments from the A/D conversion, it is important to understand the
signal source type and how to connect the analog input signals.
Types of 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.
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 DAQ-/DAQe-
2213/2214 card, assuming that the computer is plugged into the
same power system. Non-isolated out-puts of instruments and
devices that plug into the buildings power system are ground-ref-
erenced signal sources.
Input Configurations
Single-Ended Connections
A single-ended connection is used when the analog input signal is
referenced to a ground that can be shared with other analog input
signals. There are two types of single-ended connections: RSE
and NRSE. In RSE configuration, the DAQ-/DAQe-2213/2214
card provides the grounding point for the external analog input sig-
nals and is suitable for floating signal sources. In the NRSE config-
uration the board does not provide the grounding point, the
external analog input signal provides its own reference grounding
point and is suitable for ground-referenced signals.