I am new to this field and have some questions about sinking and sourcing. I understand NPN is sinking and PNP is sourcing. I also understand that an NPN device switches the common and PNP switches the positive. If I use a PNP input device, such as a prox. I need a Sinking input card? If I use a NPN input device I need a Sourcing input card? If I have a pnp output device do I need a sourcing output card? This is still a bit a confusing to me. Any help is appreciated.

Your understanding is correct.
PNP output is sourcing and NPN is sinking.
The Allen Bradley definitions for inputs are opposite.
They judge by the input itself being a sourcing or sinking load.

So if I have a pnp input device, I have to buy an Allen Bradley sinking card? Has any one ever worked with Balluff multi port input devices? Are they the same as AB as far as they way they reference their blocks as sinking and sourcing. I have an application where I have sinking input devices that I will wire to a Balluff block and I want to make sure I order the right stuff. I ran all this by my rep, but he seemed confused.

if you can give us a specific model number and a link to the manufacturer's website, maybe we can take a look at the wiring diagrams (assuming that the manual is available on the web) ... we can tell you more once we have something to look at ...

best regards,
Ron