Disclosed is a processor element including a plurality of power supply interfaces, a plurality of power supply switches, and a fault-testing unit for testing whether a short-circuit to a connected adjacent processor element has occurred at a power supply interface. In one case, multiple antennas are used, and the transmission is done in multiple steps or stages. This arrangement of the tensioning pulleys makes it possible to use relatively large tensioning pulleys resulting in a lower number of revolutions per unit of distance traveled, which brings about a reduction in noise from the bearings rotatably mounting the pulleys. The attachment portion has a first surface and a second surface spaced therefrom.