[Albert]

By NEAR_LENGTH I meant the focal distance.

The FAR_LENGTH is the focal length plus the working distance.

For example, if you set the focal length to 10 mm and the Working distance is 2000 mm:

• NEAR_LENGTH = Focal distance = 10 mm
  
• FAR_LENGTH = Focal distance + Working distance = 2010 mm
  

The distance calculation formula should not return negative values. It should give you the distance from the sensor plane (reference frame in RoboDK), instead of the focal point.

Let us know if something doesn't make sense.