Chapter 4 Signal ConnectionsVXI-MIO Series User Manual4-10 National Instruments CorporationIn NRSE mode, the AISENSE and AISENSE2 signals are connectedinternally to the negative input of the VXI-MIO Series module PGIAwhen their corresponding channels are selected. In DIFF and RSEmodes, the AISENSE/AISENSE signals are left unconnected.AIGND is an analog input common signal that is routed directly to theground tie point on the VXI-MIO Series modules. You can use thissignal for a general analog ground tie point to your VXI-MIO Seriesmodule if necessary.Connection of analog input signals to your VXI-MIO Series moduledepends on the configuration of the analog input channels you are usingand the type of input signal source. With the different configurations,you can use the PGIA in different ways. Figure 4-2 shows a diagram ofyour VXI-MIO Series module PGIA.Figure 4-2. VXI-MIO Series PGIAThe PGIA applies gain and common-mode voltage rejection andpresents high input impedance to the analog input signals connected toyour VXI-MIO Series module. Signals are routed to the positive andnegative inputs of the PGIA through input multiplexers on the module.The PGIA converts two input signals to a signal that is the differencebetween the two input signals multiplied by the gain setting of theamplifier. The amplifier output voltage is referenced to the board-InstrumentationAmplifier-MeasuredVoltageVm++PGIAVin+Vin-Vm = [Vin+ - V in- ]* Gain
