National Instruments 653X - Manual (Page 110)

Appendix D Hardware Considerations
653X User Manual D-6 ni.com
You can connect the +5 V pin to the CPULL and DPULL pins to control
the bias of the 653X device control and data lines, as described in the
Power-On State section earlier in this chapter.
Caution Do not connect the +5 V power pin directly to the GND, RGND, or any output
pin of the 653X device or any voltage source or output pin on another device. Doing so can
damage the device and the computer. National Instruments is not liable for damage
resulting from such a connection.
Selecting and Terminating Cables
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, see Appendix C,
Connecting Signals with Accessories .
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.
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 653X device. It is so
crucial to terminate the cable properly with a high-speed device because
there are more transitions per unit time, sharper signal edges, and input
lines that may respond to false edges resulting from reflection.
PCI-6534 +4.65 to +5.25 VDC at 1 A
PXI-6534 +4.65 to 5.25 VDC at 250 mA
Table D-1. 653X Power Ratings (Continued)
Device Power Rating