Ramp Metering is often applied in Dynamic Traffic Management (DTM) to control the inflow onto freeways. Although traffic usually consists of different vehicle classes such as cars and trucks, these conventional ramp meter installations operate on all classes equally, thereby disregarding the traffic composition. This paper introduces a multi-class ramp meter (MCRM) which controls the traffic vehicle-class specifically. It regulates the inflow to ascertain a specified inflow composition. In this contribution, the control algorithm of multi-class ramp metering is presented. Furthermore, the effects on travel time, queue length and total delay are outlined.