Download 6034E/6035E User Manual - Artisan Technology Group

Chapter 4
Signal Connections
In single-ended mode (RSE and NRSE), signals connected to ACH<0..15>
are routed to the positive input of the PGIA. In differential mode, signals
connected to ACH<0..7> are routed to the positive input of the PGIA, and
signals connected to ACH<8..15> are routed to the negative input of the
PGIA.
Exceeding the differential and common-mode input ranges distorts your input
signals. Exceeding the maximum input voltage rating can damage the device and the
computer. National Instruments is not liable for any damages resulting from such signal
connections. The maximum input voltage ratings are listed in the Protection column of
Table 4-2.
Caution
In NRSE mode, the AISENSE signal is connected internally to the negative
input of the PGIA when their corresponding channels are selected. In DIFF
and RSE modes, AISENSE is left unconnected.
AIGND is an analog input common signal that is routed directly to the
ground tie point on the devices. You can use this signal for a general analog
ground tie point to your device if necessary.
The PGIA applies gain and common-mode voltage rejection and presents
high input impedance to the analog input signals connected to your device.
Signals are routed to the positive and negative inputs of the PGIA through
input multiplexers on the device. 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 ground for the device. Your device A/D converter (ADC) measures this
output voltage when it performs A/D conversions.
You must reference all signals to ground either at the source device or at
the device. If you have a floating source, you should reference the signal
to ground by using the RSE input mode or the DIFF input configuration
with bias resistors, see the Differential Connections for Nonreferenced or
Floating Signal Sources section in this chapter. If you have a grounded
source, you should not reference the signal to AIGND. You can avoid this
reference by using DIFF or NRSE input configurations.
Analog Input Signal Connections
The following sections discuss the use of single-ended and differential
measurements and recommendations for measuring both floating and
ground-referenced signal sources.
© National Instruments Corporation
4-9
6034E/6035E User Manual