If you are completely new to Model Builder then the following is a quick overview. All models are made-up of objects selected from menus. There are three categories of objects.
The first category is "Controls" and these provide, as the name implies, control values to the other objects in the model. A control may be driven by a value supplied from a host computer, or may be supplied from a hand-held control unit connected to an RIU attached to a TDM ring, or alternatively from a hardware panel connected to an RIU via a PIU, or may simply be a function driven from other control values. The sample model contains examples of host driven controls and internally derived logic.
The second category of objects is "Signals". This encompasses objects that route, generate or control audio signals. This includes radios and transmitters, comm panels, intercoms, and sound generating type functions.
The final class of objects is "Feeders". These are responsible for routing the audio signals from the signal objects, and, in the case of TDM systems, controlling the routing of audio streams both from and to the RIUs on the ring.
In order to gain some understanding of how these objects are used to construct a model let us now move to examining the specifics of the sample model.