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.
Steve B