With the advancing fourth industrial revolution, different parts of smart factories have to be connected wirelessly together in order to exchange data between sensors and controlling units. Due to the increasing automation of the manufacturing process especially with the help of fast moving and rotating roboter arms it is necessary to transfer data with high reliability and in real time. Since the channels in the industrial, scientific and medical (ISM) bands are limited and more and more sensors transfer data wirelessly in the same frequency range new approaches have to be developed. In this paper a rotary coupler in coplanar grounded waveguide (CPWG) design is presented which covers the entire 2.4GHz ISM band and makes it possible to transmit data on a rotary shaft or roboter arm. The CPWG design ensures a proper shielding and increases the robustness against interference signals like WiFi or Bluetooth which results in a high reliability and makes it possible to use a high bandwidth for significantly faster communication. Design considerations, simulation and measurement results are shown. The coupler has been tested up to a rotational speed of 3300 rounds per minute (rpm).