Chapter 4
Signal Connections
4-36
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National Instruments Corporation
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 board carefully. Keep cabling away from noise
sources. The most common noise source in a PCI data acquisition
system is the video monitor. Separate the monitor from the analog
signals as much as possible.
The following recommendations apply for all signal connections to the
611X E board:
•
Separate the 611X E board signal lines from high-current or
high-voltage lines. These lines can induce currents in or voltages on
the 611X E board 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 more information, refer to the application note, Field Wiring and
Noise Consideration for Analog Signals, available from National
Instruments.
PCI_E.book Page 36 Thursday, June 25, 1998 12:55 PM