National Instruments AT E Series

Chapter4 ConnectingSignals

ATE Series User Manual 4-16 ni.com

In NRSE mode, the AISENSE and AISENSE2 signals are connected

internallyto th enegative input of the AT E Series device PGIA when their

corresponding channelsare selected. In DIFF and RSE modes, these

signalsare left unconnected.

AIGND is an AI common signal that is routed directly to the ground tie

point on the ATE Series devices. Youcan use this signal for a general

analog ground tiep ointto the ATE Series device if necessary.

Connection of AI signals to the ATE Series device depends on the

configurationof the AI channels you are using an d the type of input signal

source.With the different configurations, you can use the PGIA in different

ways.Figure 4 -4 showsa diagram of the ATE Series device PGIA.

Figure 4-4. AT E Seri es PGIA

The PGIA applies gain and common-mode voltagerej ection and presents

high input impedance to the analog input signals connected to the

ATE Series device. Signals are routed to the positive and negative inputs

ofthe PGIA throug h input multiplexerson the device. The PGIA converts

twoinpu tsi gnals to a signal that is the differencebetween the two input

signalsmultiplied by the gain setting of the ampl ifier.The amplifier output

voltageis referenced to the ground for th e device.The AT E Series device

A/D converter(ADC) measures this output voltage when it p erforms A/D

conversions.

–

PGIA

Vm=[V

in+–Vin–]* Gain

Vin+

Vin–

Programmable

Gain

Instrumentation

Amplifier

Measured

Voltage