The following central concepts are the basis of the EPLAN 21 API.
Concept |
Brief Description |
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A unique internal number which identifies an object and thus provides access to it. |
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An internal loop using which a list of objects of the same type can be searched. Iterators are used in EPLAN 21 to navigate within the data model. |
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All handles belong to exactly one session. If a session is closed all handles of this session are released. |
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A command is an object using which you can access the EPLAN 21 functions. Like all other objects of the API it is identified via a session/handle pair. |
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A property is a characteristic that is assigned to a certain object. |
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A notification is used to send messages to several reactors. |
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Callback |
A function that is registered by the EPLAN API and that can be called up for certain events. Using the callback functions, commands can e.g. be dynamically added to the system and be removed from it. |
A transaction is required when the ObjectStore database is accessed. There are two different types of transactions: ReadOnly and ReadWrite. A ReadOnly transaction only allows reading the database whereas a ReadWrite transaction also allows to modify objects in the database. |