Lenze PLC Designer PLC Designer (R3-1) - Manual (Page 381)

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DMS 4.1 EN 03/2011 TD29 379
The tab 'Placeholder' is dedicated to the following two use cases:
• Creation of a target independent project
• Creation of a library project <library_xy>, which references another library that is
meant to be target-specific, that is device-specific.
Placeholder within project
If a project shall be designed as compatible for multiple interchangeable target
devices, the target specific libraries have to be included within the library manager of
the project via placeholders.
As soon as the target device gets specified, the placeholders will be cast according to
the related device description. Even if no device description is actually available, the
placeholders allow the project to pass a syntactical check.
To include a library into the library manager via a placeholder, the library has to be
selected within the bottom part Default library of subdialog 'Placeholder'. Thereby it is
possible to constrict the catalogue of proposed libraries according to the providing
company.
In addition the placeholder name has to be inserted in the associated edit field. To
ensure correct insertion of the name you might use the selection list offering all
placeholder names currently defined in device descriptions.
Placeholder within library project
If the library project is based on further libraries that are target-specific, that is device-
specific, these libraries have to be included in the library project via placeholders.
This means that instead of specifying one particular library for being included, a
placeholder will be inserted, which will be replaced later, when <library_xy> is used in
another project for a certain device, by the name of a device-specifically defined
library. This name must be specified in the respective device description file,
<library_xy> which assigns the placeholder name to a "real" library name.
If the library manager for any reason currently is not assigned to a device, the
placeholder will be replaced by the default library specified here in the dialog. (This for
example allows compilation of the currently edited library project without detected
errors even if no suitable device description is available at that moment.)
In the Placeholder Name field enter any string as a name for the placeholder. Further
on choose a Default library from the currently installed libraries. This is to be done like
described above for adding a library in the 'Library' subdialog and like there option
Display all versions (for experts only) might be activated to get displayed all currently
installed versions of a library.
After closing the dialog with OK, the placeholder library will be entered in the library
manager tree. When you open the Properties dialog for the a library placeholder, you
get information on the currently set default library.