EPLAN 21 Architecture

EPLAN 21 Layer Model

The EPLAN 21 architecture can be made clear by using a layer model (see illustration). The object-oriented ObjectStoreTM database manages all symbol-specific and schematic-relevant data of EPLAN 21 as objects. The layer above includes the EPLAN 21 kernel. You can find the basic functionalities of EPLAN 21 here, that were programmed in the object-oriented language C++.

The "EPLAN 21 API" layer based on this language offers a single, generic function set (C-function), with which you can handle various object types (projects, pages, devices) and individual commands. A command is an object itself, which is referenced via a handle. Commands are parameterized via properties. By this, the interface gives the user the possibility to access functionalities of EPLAN 21 by using AddIns and offline programs. The "Component Object Model" shows the EPLAN 21-inherent object structures and makes it possible for the user to access the API functions via the COM interface.

The top layer consists of the "Graphical User Interface" (GUI). This includes all dialogs, the graphical editor and the Browser displaying the page-oriented view (project/page) and the logical view (project/plant/location/DT/component) as well as all open databases.

Simplified EPLAN 21 Data Model

The illustration above shows an extract of the EPLAN 21 data model. The data model includes various object types or lists of objects with specific properties. You can distinguish between graphic and logical information. The graphic information of a schematic is managed on pages. These pages store the instances on layers. The corresponding classes are Page, Layer, and Instance. The classes Device, Component, Terminal and Connection and other are offered for logical information.

The Project class manages the entire logical and graphic information of a schematic (e.g. project name, company, and formatting properties). On a logical page a project contains any number of devices with the properties "Electrical characteristics", "Plant/location designation", or "Function text". The device is composed of at least one component. The device 'contactor' includes for example the components 'coil' and 'contact'. A component may have any number of connections. The Terminal class contains information on wires going through the connection. There may be any number of wires between the connections. The Connection class includes electrical connections. It contains information on the connections that belong to this wire (e.g. "wire number", "wire name" or "conductor color"). A wire comprises exactly two connections.

A project contains a list of page types on the graphics page. This may be title page, table of contents, and schematic pages. The properties offered are for instance page name, plant/location designation, and editor identifier. A page may have any number of levels. On one level you can place as many property instances as you like. These are instantiated components in the form of graphic primitives, texts and symbols. Each component can only be represented on a page by a graphic property instance, and each property instance belongs to exactly one component. A symbol is already assigned to each component before it is instantiated in the schematic.

EPLAN 21 Object Model

The illustration below shows the relation between the individual objects of the EPLAN 21 data model. In addition, the respective iterators are given using which you can access the objects.