ISO-tapping machines are used as a standardised excitation when measuring impact noise. It is required that 5 hammers with a mass of 500 g each impact the floor at a velocity of 886 mm/s at time intervals of 0.1 s. There are several other requirements like the distance between the hammers, the hammer diameter and the radius of the impact surface of the hammer. These requirements are today defined in different international standards but there is an activity ongoing to develop a new standard ISO/PWI 21791 “Acoustics – Sound sources for building acoustics” which shall also cover the testing of tapping machines.The current standards prescribe that some of the parameters have to be measured only once like the distance between the hammers whereas other parameters shall be checked regularly like the velocity at impact and time between impacts. The contribution introduces an alternative periodic test of ISO tapping machines which is based on a simultaneous measurement of the acting force at each of the five hammer positions. Results of test measurements are presented and conclusions with respect to the applicability of such a method are derived.