This class is the base for all the switched channels. A switched channel is the mapping between a modulation and an actual physical output (be it ttl, analog, gpib etc). Whereas a modulation describes the type of modulation being performed (i.e. analog, digital) the switched channel corresponds to how that modulation is performed. For example it's perfectly reasonable to have an analog modulation associated with a TTLSwitchedChannel if the analog current is switched by a digitally driven box.