Chapter 3
Signal Connections
©
National Instruments Corporation
3-5
Analog Input Signal Connections
Pins 1 through 8 are analog input signal pins for the 12-bit ADC. Pin 9,
AISENSE/AIGND, is an analog common signal. You can use this pin for
a general analog power ground tie to the PCI-1200 in RSE mode or as a
return path in NRSE mode. Pin 11, AGND, is the bias current return point
for differential measurements. Pins 1 through 8 are tied to the eight
single-ended analog input channels of the input multiplexer through 4.7 k
Ω
series resistors. Pins 2, 4, 6, and 8 and also tied to an input multiplexer for
DIFF mode.
The signal ranges for inputs ACH<7..0> at all possible gains are shown in
Tables 3-2 and 3-3. Exceeding the input signal range will not damage the
input circuitry as long as the maximum powered-on input voltage rating
of ±35 V or powered off voltage rating of ±25 V is not exceeded. The
PCI-1200 is guaranteed to withstand inputs up to the maximum input
voltage rating.
Caution
Exceeding the input signal range distorts input signals. Exceeding the maximum
input voltage rating may damage the PCI-1200 board and the computer. National
Instruments is
NOT
liable for any damages resulting from such signal connections.
Table 3-2.
Bipolar Analog Input Signal Range Versus Gain
Gain Setting
Input Signal Range
1
–5.0 to 4.99756 V
2
–2.5 to 2.49878 V
5
–1.0 to 0.99951 V
10
–500 to 499.756 mV
20
–250 to 249.877 mV
50
–100 to 99.951 mV
100
–50 to 49.975 mV
Table 3-3.
Unipolar Analog Input Signal Range Versus Gain
Gain Setting
Input Signal Range
1
0 to 9.99756 V
2
0 to 4.99878 V
!
