Chapter 3 Signal Connections
© National Instruments Corporation 3-7 SC-2040 User Manual

Analog Signal Inputs

Connect the differential signals to be measured to the screw terminal connectors J1 through J4
and J5 through J9.
DC-Coupled Inputs
Note: If all your inputs are DC-coupled, leave connector J5 disconnected.
All eight channels have fully differential inputs, so the signals you are measuring should be
ground referenced. If they are not, set jumpers W2 through W9 of the nonreferenced channels to
position B-C to create a DC path for the input bias currents. If you do not do this, the bias
currents of the instrumentation amplifiers of the nonreferenced channels produce stray
capacitances, resulting in uncontrollable drift and possible saturation.
Figure 3-3 illustrates how to connect a ground-referenced signal.
A
IN-
IN+
100 kΩSC-2040
Vin
A B C
CH+
CH-
Figure 3-3. Ground-Referenced Signal Connection