The system comprises a master module and slave modules able to be chain-connected andor star-connected by means of a digital communication network, for example of the Ethernet type. The lock body has a slot for receiving a projection extending out of the sleeve member and permits the projection sliding along the slot. Compensation is designed to render the mathematical model passive in the sense of mathematical system theory. by reducing the size of a frame’s fram-start-sequence by a predetermined amount, whereby interconnection failure may be diagnosed by analysing the frame-start-sequence. Most preferably, the domain manager has substantially direct access to the shared registry system, which asynchronously updates the DNS servers. When an inrush current flows at the start of driving of the load, an integrator 10 provided to the gate of the FET is operated to mitigate the rising characteristics of the pulse signal.