Configuring Ai Ground-Reference Settings In Software; Multichannel Scanning Considerations - National Instruments DAQ X Series User Manual

Chapter 4 Analog Input
AI ground-reference setting is sometimes referred to as AI terminal
configuration.
Configuring AI Ground-Reference Settings in
Software
You can program channels on an MIO X Series device to acquire with
different ground references.
To enable multimode scanning in LabVIEW, use
Virtual Channel.vi
each channel or group of channels configured in a different input mode. In
Figure 4-3, channel 0 is configured in differential mode, and channel 1 is
configured in RSE mode.
To configure the input mode of your voltage measurement using the DAQ
Assistant, use the Terminal Configuration drop-down list. Refer to the
DAQ Assistant Help for more information about the DAQ Assistant.
To configure the input mode of your voltage measurement using the
NI-DAQmx C API, set the terminalConfig property. Refer to the
NI-DAQmx C Reference Help for more information.

Multichannel Scanning Considerations

MIO X Series devices can scan multiple channels at high rates and digitize
the signals accurately. However, you should consider several issues when
designing your measurement system to ensure the high accuracy of your
measurements.
In multichannel scanning applications, accuracy is affected by settling
time. When your MIO X Series device switches from one AI channel to
another AI channel, the device configures the NI-PGIA with the input range
of the new channel. The NI-PGIA then amplifies the input signal with the
gain for the new input range. Settling time refers to the time it takes the
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of the NI-DAQmx API. You must use a new VI for
Figure 4-3. Enabling Multimode Scanning in LabVIEW
4-6
NI-DAQmx Create
ni.com