The R1005050 and NB5 cables differ in the type of 100-pin connector and the pin assignments on the 50-pin connectors. The NB5 cable is only compatible with the PC-DIO-96 and PC-DIO-96/PnP, while the R1005050 is used with other boards with 100 pin connectors such as the PCI-DIO-96, PXI-6508, PCI-6509, PCI-6527, PXI-6527, and PCI-6025E.
Due to the variety of devices which can potentially utilize the R1005050 and NB5 cables, pin-outs should be obtained from the manual for your device. For example, page 18 of the PCI-DIO-96/PXI-6508/PCI-6503 user manual will display the pin-out of the R1005050 cable. Each 50 pin connector is labeled as either pins 1-50 or 51-100 and the below images can be used to determine the numbering sequence of the 50 pin connectors.