Today’s digital factory needs a large variety of different robot systems. For this purpose, the paper presents an approach which assembles the control software with standard function blocks for different axis groups and tests it with a digital twin. The robot simulation is based on the gaming software UnReal and can easily be adapted to different kinematics by specifying the Denavit-Hartenberg parameters. After successful virtual commissioning, the robot hardware is assembled as modularly as the control software by means of individual axes.