National Instruments NI 783xR Manuel D’Utilisation

Environmental noise can seriously affect the measurement accuracy of the 
device if you do not take proper care when running signal wires between 
signal sources and the device. The following recommendations mainly 
apply to AI signal routing to the device. They also apply to signal routing 
in general.

Take the following precautions to minimize noise pickup and maximize 
measurement accuracy:

•

Use differential AI connections to reject common-mode noise.

•

Use individually shielded, twisted-pair wires to connect AI signals to 
the device. With this type of wire, the signals attached to the positive 
and negative inputs are twisted together and then covered with a shield. 
You then connect this shield only at one point to the signal source 
ground. This kind of connection is required for signals traveling 
through areas with large magnetic fields or high electromagnetic 
interference.

•

Route signals to the device carefully. Keep cabling away from noise 
sources. The most common noise source in a PXI DAQ system is the 
video monitor. Keep the monitor and the analog signals as far apart as 
possible.

Use the following recommendations for all signal connections to the 
NI 783xR:

•

Separate NI 783xR signal lines from high-current or high-voltage 
lines. These lines can induce currents in or voltages on the NI 783xR 
signal lines if they run in parallel paths at a close distance. To reduce 
the magnetic coupling between lines, separate them by a reasonable 
distance if they run in parallel or run the lines at right angles to each 
other.

•

Do not run signal lines through conduits that also contain power lines.

•

Protect signal lines from magnetic fields caused by electric motors, 
welding equipment, breakers, or transformers by running them through 
special metal conduits.

Refer to the NI Developer Zone tutorial, Field Wiring and Noise 
Considerations for Analog Signals, at 

ni.com/zone

 for more information.