User manual

Chapter 4 Connecting Signals
NI 6034E/6035E/6036E User Manual 4-8 ni.com
Figure 4-2. Programmable Gain Instrumentation Amplifier (PGIA)
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.
Caution
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.
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
+
+
–
–
PGIA
V
m
=[V
in+
–V
in–
]* Gain
V
in+
V
in–
V
m
Programmable
Gain
Instrumentation
Amplifier
Measured
Voltage
UM.book Page 8 Monday, May 14, 2001 10:32 AM