This paralllely indexing cam is not ordinary cam. In normal cam the X axis is angle and Y axis is linear displacement of the cam. This cam is both X and Y axis are anglular values. The output is rotation and not a linear displacement.
That's why I've mentioned also Globoidal Cam. It also nearly same as parallel indexing cam. The roller axis perpendicular in Globoidal cam and parallel in Parallel indexing drive. Even parallel indexing cam having a single profile but Globoidal cam having multiple profiles.