A method for operating a test apparatus including a plurality of shared resources is shown, wherein the plurality of shared resources can be used in different instruments. The method includes blocking a first set of resource blockers when a first instrument, which requires a first subset of the shared resources, is to be executed. Furthermore, the method tries to block a second set of resource blockers, when a second instrument, which requires a second subset of the shared resources, is to be executed. Therefore, the first set of resource blockers is different from the second set of resource blockers and a plurality of resource blockers are assigned to a shared resource, which is involved in a conflicting combination of instruments and in a non-conflicting combination of instruments.