Chapter 4 Signal ConnectionsPCI-6110E/6111E User Manual4-8 ©National Instruments CorporationAnalog Input Signal ConnectionsThe analog input signals for the 611X E board are ACH<0..3>+ andACH<0..3>–. The ACH<0..3>+ signals are routed to the positive inputof the PGIA, and signals connected to ACH<0..3>– are routed to thenegative input of the PGIA.Caution: Exceeding the differential and common-mode input ranges distorts yourinput signals. Exceeding the maximum input voltage rating can damagethe 611X E board and the computer. National Instruments is NOT liable forany damages resulting from such signal connections. The maximum inputvoltage ratings are listed in the Protection column of Table 4-2.With the different configurations, you can use the PGIA in differentways. Figure 4-2 shows a diagram of your 611X E board PGIA.Figure 4-2. 611X E Board PGIAThe PGIA applies gain and common-mode voltage rejection andpresents high input impedance to the analog input signals connected tothe 611X E board. Signals are routed to the positive and negative inputsof the PGIA. The PGIA converts two input signals to a signal that is thedifference between the two input signals multiplied by the gain settingof the amplifier. The amplifier output voltage is referenced to theground for the board. The 611X E board A/D converter (ADC) measuresthis output voltage when it performs A/D conversions.!-InstrumentationAmplifier-MeasuredVoltageVm++PGIAVin+Vin-Vm = [Vin+ - V in-]* Gain
