National Instruments 653X Manuale Utente

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 

 section earlier in this chapter.

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.

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, 

.

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)