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NI 6561: 36MHz clocked data

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I need to send/receive LVDS data to/from a product. The data must be clocked at 36MHz and the clock must be sent as well to the product.

Can you confirm that, if I use a PCI 6561:

- I need an external 36 MHz clock, connected to the CLK IN jack (the on-board clock can't be used?)

- I must export the sample clock on one of the CLK OUT ports

Thanks for your help,



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Accepted by topic author Anne B.

Hi Anne,


You are correct on all counts.  The 6561 can only generate frequencies of 200MHz/N with its onboard clock.  You could get 40MHz or 33.3MHz, but not 36MHz.  You can connect a 36MHz clock source to CLKIN and use that as your sample clock source.  You can also export that clock with your data (if you use the DDC Clock Out terminal, the data and clock will have a guaranteed phase relationship).


Hope that helps,


Keith Shapiro

National Instruments R&D

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