Analog Input - National Instruments M Series User Manual

Analog Input

Figure 4-1 shows the analog input circuitry of M Series devices.
Figure 4-1. M Series Analog Input Circuitry
AI <0..207>
Mux
AI SENSE
AI GND
The main blocks featured in the M Series analog input circuitry are as follows:
I/O Connector—You can connect analog input signals to the M Series device through the
•
I/O connector. The proper way to connect analog input signals depends on the analog input
ground-reference settings, described in the
section. Also refer to Appendix A,
connector pinouts.
Mux—Each M Series device has one analog-to-digital converter (ADC). The multiplexers
•
(mux) route one AI channel at a time to the ADC through the NI-PGIA.
Ground-Reference Settings—The analog input ground-reference settings circuitry selects
•
between differential, referenced single-ended, and non-referenced single-ended input
modes. Each AI channel can use a different mode.
Instrumentation Amplifier (NI-PGIA)—The NI programmable gain instrumentation
•
amplifier (NI-PGIA) is a measurement and instrument class amplifier that minimizes
settling times for all input ranges. The NI-PGIA can amplify or attenuate an AI signal to
ensure that you use the maximum resolution of the ADC.
M Series devices use the NI-PGIA to deliver high accuracy even when sampling multiple
channels with small input ranges at fast rates. M Series devices can sample channels in any
order at the maximum conversion rate, and you can individually program each channel in
a sample with a different input range.
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DIFF, RSE,
NI-PGIA
or NRSE
Input Range
Selection
AI Terminal
Configuration
Selection
Analog Input Ground-Reference Settings
Module/Device-Specific
4
ADC AI FIFO AI Data
Information, for device I/O
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