© National Instruments
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4-1
4
Analog Input
Figure 4-1 shows the analog input circuitry of M Series devices.
Figure 4-1.
M Series Analog Input Circuitry
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
Analog Input Ground-Reference Settings
section. Also refer to Appendix A,
Module/Device-Specific Information
, for device I/O
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.
DIFF, R
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or NR
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I/O Connector
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AI
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AI GND
NI-PGIA
AI Termin
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Config
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Inp
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ADC
AI FIFO
AI D
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