NI advertises the RDIO 68 cable for high speed digital interface to R series PXI boards such as the 7811R. The unpublished impedance of the RDIO was given to me
as ~90 ohms however the details of the termination network used (which is embedded in the RDIO cable end) are not available. My question is:
1. Why does NI suggest this cable for high speed interface but does not provide the required information to design a matched drive signal that will minimize ringing and signal reflection?
I have tried a variety of techniques using series terminations, HC and LS line drivers but cannot do any better than the attached scope trace which reveals a significant signal reflection.
