An apparatus (1) for applying stimulation to a body has a distributed control system comprising a first CPU (7) in a main unit (24), a second CPU (30) in a display and control unit (2) and a further CPU 5 in each of one or more interface cards (3, 4). The second CPU (30) is configured to control the operation of the first CPU (7), while the first CPU (7) is configured to control and coordinate the operation of the CPUs (5) in each interface card (3, 4).
