First, if your device under development is a PXI type, not a PXI Express(PXIe), check this KB
about PXI pinout.
You can find the pinouts at the end of the PXIe chassis user manual based on your model.
However, you may need more references to understand how to apply this to your model.
PXIe is a standard that leverages the electrical features defined by the widely adopted PCI Express specification for data movement.
Refer to the PXI Express Hardware Specifications at pxisa.org
for more information.