A current measurement circuit and method for testing a semiconductor device is provided. The hardware unit has a processing element and a memory. A second sheet of the security document has a carrier layer and one or more electrically conductive layers shaped in a second region for the formation of at least one LCR resonant circuit. A guide prevents the link carriage from moving past a location along the first travel path, and, in response, the pivot link pivotally moves to cause the link carriage to move along a second travel path and thereby move the port door toward or away from the port plate aperture, depending on the direction of movement of the drive carriage along the first travel path relative to the link carriage.