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Further Study on CoDeSys

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1. CoDeSys requires device vendors to ship products with so called target support package. By installing this drivers pack, different vendors’ devices could be accessed in Programming Tool. At run-time, the CoDeSys control codes are executed with support of a standard CoDeSys run-time system in devices.

2. CoDeSys software provides programming functionality, communication block and portable protocol stack.

3. OOP

4. FieldBus devices and Controller I/O Configuration

4. Simulation
CoDeSys can simulate target devices including Controller, Field bus devices etc. This is realized by loading specific libraries in the confifuring system. Just like Step 3 in I/O configuration above.

5.Library –Multiple versions of the same library can be installed on the system.
CoDeSys support lots of vendor lib and custom lib. In general there are 4 categories of libs and category information is maintained in “LibraryCategoryBase.Libcat.xml”.

“PlaceHolder” is proposed to use target specific libs transparently, do casting when running.

  • 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.

  • 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.

  • Question: Version 3.4 CoDeSys did not offer the “Placeholder” sub dialogue when adding libraries.

With the “Placeholder”, user can pointer at external libs and link them at run-time.

If libraries have different versions, user can indicate which version to use by “Placeholder”. If no “Placeholder”, the newest version lib will be used by Interface lib, “Template Library”. In addition, “Namespace” is also used to differentiate lib versions.

6. Symbol Configuration

The Symbol configuration is used to create symbols, provided with specific access rights, via which project variables can be accessed from external, for example by an OPC Server. The description of the symbols (symbol information) will be available in a xml-file (symbol file) in the project directory, and it will be downloaded to the PLC together with the application.

The symbol configuration editor provides two tools to define a set of symbols which will be exported. In a
first step it is possible to define a set of variables / instances below the Variables node of the configurator. This can also be achieved by selecting some members of an data type below the Data Types node in the configurator.

Written by laurence yuyi

December 30, 2010 at 4:26 pm

Posted in Technology

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