National Instruments SCB-68 User Manual
Page 42
Chapter 3
Connecting Signals
SCB-68 Shielded Connector Block User Manual
3-14
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ACH+ and ACH– inputs are twisted together and then covered with
a shield. You then connect this shield at only 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. A common noise source in DAQ applications is the
computer monitor. Separate the monitor from the analog signals as
far as possible.
The following recommendations apply for all signal connections to the
DAQ device:
•
Separate DAQ device signal lines from high-current or
high-voltage lines. These lines can induce currents in or voltages on
the DAQ device 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.
For information about minimizing noise in your application, refer to the
NI Developer Zone tutorial, Field Wiring and Noise Considerations for
Analog Signals, located at
ni.com/zone
.