National Instruments 1142 用户手册

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The SCXI-1141/1142/1143 module instrumentation amplifiers can reject 
any common-mode voltage within their common-mode input range caused 
by ground-potential differences between the signal source and the module. 
In addition, the amplifiers can reject common-mode noise pickup in the 
leads connecting the signal sources to the SCXI-1141/1142/1143 module. 
However, you should take care to minimize noise pickup. The 
common-mode rejection of the instrumentation amplifiers decreases 
significantly at high frequencies. The amplifiers do not reject 
normal-mode noise.

The maximum differential input voltage range of the 
SCXI-1141/1142/1143 module instrumentation amplifiers is a function of 
the gain of the amplifiers, G, and is equal to 5 V/G. The common-mode 
input range of the SCXI-1141/1142/1143 module, however, is not a 
function of gain—the differential input amplifier rejects common-mode 
signals as long as the signal at both inputs is within ±5 V of the module 

A32, A30, A26, A24, 
A20, A18, A14, A12

AI+<0..7+>

Positive input channels—these pins connect to the 
noninverting inputs of the instrumentation amplifier 
of each channel.

C32, C30, C26, C24, 
C20, C18, C14, C12

AI–<0..7–>

Negative input channels—these pins connect to the 
inverting inputs of the instrumentation amplifier of 
each channel.

A28, A22, A16, C28, 
C22, C16

A GND

Analog ground—these pins connect to the module 
analog ground.

A2, C8

D GND

Digital ground—these pins connect to the module 
digital ground.

A8, A6, A4, C8

RSVD

Reserved—do not connect any signals to these pins.

C4

EXT CLK

External clock—you can use this signal to set the 
filter cutoff frequency.

C2

OUT CLK

Output clock—this signal has a frequency that is 
proportional to the cutoff frequency. You can use this 
signal to externally control the cutoff frequency.

Note: All other pins are not connected.