Functions: Principle

From the electrical point of view, a function is a subelement of an item. An item can have one or more functions, but a function can only be assigned to a single item. An auxiliary block on the contactor, for example, can contain two NO contacts and one NC contact, so that it contains three functions.

From a data processing point of view, a function is an object which is assigned a function definition, and consists of a group of connection points.

EPLAN differentiates between main functions and auxiliary functions, where the main function represents the main item.

The logic of the functions is a result of the function definitions, which are provided by EPLAN as master data.

The function is therefore the smallest logical unit which is managed by EPLAN in the data model. The connection points of a function are embedded in it and managed in it, and can therefore only be seen in connection with the function. Between the connection points, the connection point logic is managed within the functions (potential interruption, PLC target tracking, etc.).

Representation of functions

Once an object is created in the project and a function definition is assigned to it, this object becomes a function. If the function is also represented by a symbol on a schematic page, we then speak of a component. Only one function can be assigned to a component at one time.

When drawing a schematic, not the items, but the individual functions are placed. In the navigator dialogs, unplaced functions can also be managed, i.e. functions to which there is no symbol assigned.

Change the properties of functions

If a function is used in a project, then the function definition in turn provides particular pre-defined properties. The function definition data is only comprised of default values and can be overwritten for every individual component. You can also add extra properties.

So for instance the logic (the connection point data) can be adapted to an individual function. If a terminal should not transmit signals, for instance, although it is defined as doing so in the function definition, then you can set this individually for this one terminal. Or, if the tracking of a change-over contact should not go to the closed side but to the open side, then you can configure that individually for this single change-over contact.

You can specify for each individual component whether it performs signal isolation, and therefore represents a limit for connection numbering.

Behavior of properties when switching function definitions

The data you entered for the old function (e.g. function text, DT, etc.) is retained when you switch function definitions. The connection point logic, however, is overwritten by the new function definition.

When changing the function definition on a function, it can occur that properties which were once available are no longer available afterwards. The properties are still retained and will become visible again if you select a different function definition for which they are available.

When compressing the project, these properties are removed.

Use existing functions

In the component-specific tabs (such as the Interruption point tab, the Shield tab, etc.) of the Property dialog, in the Displayed DT field you can click [...] to display all DTs present in the project which match the given function, and use an existing function. Please note the following:

If when you use an existing function the name is highlighted, only this will be used; all other data (such as function text, mounting site, etc.) will be ignored.
On the other hand, if an individual function is highlighted, the data on the Symbol / function data and Display tabs is not changed, but all editable properties of the selected function are used apart from the representation-specific properties from the 'Settings' category.