Hi hkhalili,
The myRIO-1900 and myRIO-1950 only have single-ended DIO. Currently, if you require LVDS signalling and have a background in hardware design, the sbRIO-9651 has both LVDS input and output capability. The sbRIO-9651 is a System on Module (SOM) and requires the development of a carrier board things like supplying power as well as breaking out the DIO required for your application.
The sbRIO-9651 is certainly a step up in the flexibility and configuratbility of a RIO product, but it also comes with a steeper learning and development curve.
Tannerite
National Instruments