This article shows the pin assignments on the R1005050 and NB5 ribbon cables (this cable was made "End of Life" in 2016). It also compares and explains the differences between the R1005050 cable (previously NB6) and the NB5 cable.
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.