National Instruments 653 Series User Manual page 110

Appendix D Hardware Considerations
Do not connect the +5 V power pin directly to the GND, RGND, or any output
Caution
pin of the NI 653X or any voltage source or output pin on another device. Doing so can
damage the device and the computer. NI is not liable for damage resulting from such a
connection.
Selecting and Terminating Cables
Tip Cables that do not meet the above requirements, such as ordinary ribbon cables,
should only be used for short distances and for applications where signal reflections are not
a concern, because they cannot be properly terminated.
NI 653X User Manual
Table D-1. NI 653X Power Ratings (Continued)
Device
NI PCI-6534
NI PXI-6534
You can connect the +5 V pin to the CPULL and DPULL pins to control
the bias of the NI 653X control and data lines, as described in the
State section.
It is important to select an appropriate cable and to properly terminate it to
avoid undershoots, overshoots, and reflections. The SH6868-D1 is a
twisted-pair cable. Each signal conductor is twisted with a ground
conductor that establishes a low-inductance uniform transmission line.
For more information about this cable and other accessories, refer to
Appendix C, Connecting Signals with
Without termination, any sharp transition in a signal can lead to
overshooting above 5 V, undershooting below 0 V, or false edges due to
reflections ("ringing"). Proper termination is recommended for low-speed
transfers as well as high-speed devices like your NI 653X. It is crucial to
properly terminate the cable with a high-speed device because there are
more transitions per unit time, sharper signal edges, and input lines that
might respond to false edges resulting from reflection.
+4.65 to +5.25 VDC at 1 A
+4.65 to 5.25 VDC at 250 mA
Accessories.
D-6
Power Rating
Power-On
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