Mark,
The connectors that Tayyab mentions are for developing PCB adapter cards that mate via cable (or sometimes direct connector) to the front of the existing PXI instruments (most). If you see a standard NI PXI card and you'd like to develop a custom connector this is the best scenario.
If you are wanting to design your own PXI card from the ground up, you can certainly do that with Multisim. If you need a custom PXI board outline I can also get you that (I don't believe it is built as a template yet in Multisim/Ultiboard). However it will be a very basic board outline + a few of the back PXI interface connectors. Let me know if this is what you want. A better option (will get you a custom PXI board faster) is the custom FlexRIO environment which provides you hardware+software+customization capabilties.
For Multisim, we have available a custom FlexRIO adapter board outline + connector template (gold finger connectors) that can attach to any of our PXI FlexRIO boards. The nice thing about these is you don't have to worry too much about building the low level PCI + trigger interface to PXI, but you can program the logic + special trigger requirements of the board with LabVIEW FPGA (its basically a high performance Xilinx FPGA you're programming). We've taken care of the memory, PCI and trigger interface in both hardware and software and allow you a black box in which to program the functionality of your custom PXI device. The digital I/O is connected directly to the front connector and if you need any special functionality you build it in the adapter card interface on the front (we sell the hardware kits, etc...). To access this, you do need to purchase the FlexRIO Adapter Card MDK (http://www.ni.com/white-paper/7961/en)... We sell the enclosure hardware which the FlexRIO adapter design in Multisim will fit into.
For any engineer wanting these FlexRIO adapter card design files for Multisim/Ultiboard we can send them to you after purchasing the MDK - just email one of our sales team and they will get you in touch with the Multisim application engineers. Note I am aware of many NI users that have chosen this path to build a custom FlexRIO adapter in Multisim/Ultiboard and have gotten good results in creating a high-performance custom hardware+software solution in a very rapid fashion.
Also both the FlexRIO and Multisim Application Engineers from National Instruments will be able to help you get up and running with this project.
Regards,
Pat Noonan
