Analog Input - National Instruments NI 6221 User Manual

Analog Input

AI <0..n>
Mux
AI SENSE
AI GND
© National Instruments Corporation
Figure 4-1 shows the analog input circuitry of M Series devices.
DIFF, RSE,
NI-PGIA
or NRSE
Input Range
Selection
AI Terminal
Configuration
Selection
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
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
AI Lowpass
Filter
Analog Input Ground-Reference Settings
Device-Specific
4-1
4
ADC AI FIFO
section. Also
Information, for device I/O
M Series User Manual
AI Data