Chapter 2
Analog Input
©
National Instruments Corporation
2-29
Configuring AI Modes in Software
You can program channels on an E Series device to acquire in different
modes, but once a channel mode is specified, it cannot be reused for another
mode. For example, to configure AI 0 for DIFF mode and AI 1 for RSE
mode, configure AI 0 and AI 8 in DIFF mode and AI 1 and AI GND in RSE
mode. In this configuration, AI 8 is not used in a single-ended
configuration.
Traditional NI-DAQ (Legacy)
To enable multi-mode scanning in LabVIEW using Traditional NI-DAQ
(Legacy), use the
coupling & input config
control of the AI Config VI.
This input has a one-to-one correspondence with the
channels
control of
the VI. You must list all channels either individually or in groups of
channels with the same input configuration. For example, if you want AI 0
to be differential, and AI 1 and AI 2 to be RSE, Figure 2-13 demonstrates
how to program this configuration in LabVIEW.
Figure 2-13.
AI Config VI
To enable multi-mode scanning using NI-DAQ functions, call the
AI_Configure
function for each channel.
NI-DAQmx
To enable multi-mode scanning in LabVIEW using NI-DAQmx, use the
NI-DAQmx Create Virtual Channel.vi
of the NI-DAQmx API. You
must use a new VI for each channel or group of channels configured in a
different input mode. In Figure 2-14, channel 0 is configured in differential
mode, and channel 1 is configured in RSE mode.
