Electronic devices can precisely time switch, facilitating SRM configurations. At the same time switch S closes so this voltage appears at the output. A countdown time switch switches power, usually off, after a preset time. In practice, the maximum size of switch is a 64x64 Time Switch matrix. The Communications Module (CM) forms the central time switch of the exchange. Each time switch is duplicated into two security planes, 0 and 1. Because of the running time switch, the half-hour episodes contain 3 segments instead of 2.