Use the Occupy Backsight setup routine with MAGNET Construct
MAGNET Construct - Occupy Backsight Setup Routine

There are multiple equipment setup options to choose from within MAGNET Construct. Check out this video for an overview of the traditional method commonly referred to as "occupy / backsight".
In this method, the Topcon LN-100 has physically been set over an existing control point on your project site and is then expected to be oriented towards a second existing control point.
The MAGNET Construct app will then drive your Topcon LN-100 and solve for it's orientation. Could not be easier.
Watch the video to learn how.