To record, control and monitor processes the exchange of process data between a PLC and zenon as well as the sending of values and commands in the other direction is necessary. The basis of this data exchange are process variables (lateron simply called variables). These represent the value in PLC and visualisation and consist of a number of definable properties such as name, measuring range, signal resolution, unit, decimals, limits, etc.). A more detailled description of these properties is in the properties help in the Editor. Variables are the interface between the data source (PLC, field bus, etc.) and zenon. The variables are defined in the central variable list and are available her from everywhere (functions, pictures, archives, etc.). Higher level projects (integration projects) can directly access the variables of lower level projects.
A variable is always based on two components: Data type and driver object type. These two components are independent and thus can be configured independently.