National Instruments VXI-MIO Series - page 56

Chapter 4 Signal Connections
VXI-MIO Series User Manual 4-10  National Instruments Corporation
In NRSE mode, the AISENSE and AISENSE2 signals are connected
internally to the negative input of the VXI-MIO Series module PGIA
when their corresponding channels are selected. In DIFF and RSE
modes, the AISENSE/AISENSE signals are left unconnected.
AIGND is an analog input common signal that is routed directly to the
ground tie point on the VXI-MIO Series modules. You can use this
signal for a general analog ground tie point to your VXI-MIO Series
module if necessary.
Connection of analog input signals to your VXI-MIO Series module
depends on the configuration of the analog input channels you are using
and the type of input signal source. With the different configurations,
you can use the PGIA in different ways. Figure 4-2 shows a diagram of
your VXI-MIO Series module PGIA.
Figure 4-2. VXI-MIO Series PGIA
The PGIA applies gain and common-mode voltage rejection and
presents high input impedance to the analog input signals connected to
your VXI-MIO Series module. Signals are routed to the positive and
negative inputs of the PGIA through input multiplexers on the module.
The PGIA converts two input signals to a signal that is the difference
between the two input signals multiplied by the gain setting of the
amplifier. The amplifier output voltage is referenced to the board
-
Instrumentation
Amplifier
-
Measured
Voltage
Vm
+
+
PGIA
Vin+
Vin-
Vm = [Vin+ - Vin-]* Gain