Hi blaber,
The driver that can be used with the 6509 is NI-DAQmx. You can download the driver from our Drivers and Updates page and locating the NI-DAQmx driver. When you install the driver be sure to add framework support for .Net 1.1 and/or 2.0 depending on your environment. If you already have the driver installed you can add the support by going to Control Panel>>Add or Remove Programs>>National Instruments Software>>Change/Remove>>NI-DAQmx x.x>>Modify. You can expand Data Acquisition>>NI-DAQmx x.x and select to install the .Net framework support and examples.
You can locate the DAQmx C# examples to use as a programming guide. The examples should install in the same area as the ANSI C examples and you can find more information about that location in the KnowledgeBase link that I included.
Drivers and Updates<a href="http://joule.ni.com/nidu/cds/fn/p/lang/en" target="_blank">http://joule.ni.com/nidu/cds/fn/p/lang/en</a>
Location of ANSI C NI-DAQmx Shipping Examples and DAQmx Library File for Windows<a href="http://digital.ni.com/public.nsf/allkb/FB26BDA52FFFD4EE86257124005C36C3?OpenDocument" target="_blank">http://digital.ni.com/public.nsf/allkb/FB26BDA52FFFD4EE86257124005C36C3?OpenDocument</a>