A head assembly having a sensor element on the head assembly. The Hall generator, control current supply circuit, and Hall voltage output circuit are all exposed at one of the pair of opposite major surfaces of the semiconductor substrate. Air handlers or air conditioning units may be mass produced in common configurations, and installed in different buildings or structures with different ductwork configurations. The staff activity assignment is communicated from the access control system to the process server. Other embodiments may be described and claimed. The truck restraining device has a lock assembly comprising a base and a locking arm pivotally mounted to the base for rotating between retracted and extended positions.