First, it is important to understand that each device or module may use its own pinout or pin mapping scheme. Typically, families of devices with the same pin count will use the same numbering and signal combinations. Always verify you are using the correct pinout for your device. There are several resources you can use to find this scheme.
Figure 2 is an example of a device pinout for a multifunction data acquisition card, PXIe-6361. Figure 3 shows an example device pinout for one of the cDAQ modules, NI-9401.
Figure 3. NI 9401 Device Pinout.
All accessories, with the exception of PXI front mounted blocks, connect to a device or module through a cable. Unless creating a custom breakout box or test fixture, it's typically unnecessary to understand the pin mapping at each cable and device connector. Instead, you can take the above information from above in regards to the signal mapping, and use that to wire to the labeled numerical screw or BNC terminals once you have connected your cable.