Regarding NcDataReader

This page contains work in progress, so if we miss anything or you have a better way, please let us know.

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The BuildingSystems library includes the netCDF reader NcDataReader from Jörg Rädler. This page does not consider the usage of this plugin, but a detail in its implementation, which in our experience comes along with some problems. These problems have been reproduced with different versions of Dymola.

The directory \BuildingSystems\Utilities\LibrariesNcDataReader2 contains files, which are used by the NcDataReader (11 elements). The reader itself is integrated in the BuildingSystems library as a subpackage in BuildingSystems\Utilities\NcDataReader2.

The package contains following files:

ncEasyGet1D
ncEasyGetAttributeDouble
ncEasyGetAttributeLong
ncEasyGetAttributeString
NcDataReader
ExampleNcDataReader

Except NcDataReader, all files call external libraries or header files from the above mentioned directory.

There are three possible ways to call these files: using absolute or relative paths.
All of them have their advantages and disadvantages.

Using loadRessources

A short documentation for loadResources functionality could be found here.

Corresponding source code could be found e.g.in BuildingSystems.Utilities.NcDataReader2.Example:

fileName = Modelica.Utilities.Files.loadResource("modelica://BuildingSystems/Climate/weather/WeatherDataNetcdf/Germany_HamburgTRYnormal_weather.nc");

or e.g. in BuildingSystems.Utilities.NcDataReader2.ncEasyGet1D as part of an annotation:

annotation (Include="#include <ncDataReaderEA.h>",IncludeDirectory=
             "modelica://BuildingSystems/Utilities/LibrariesNcDataReader2/",                                                             
            Library={"ncDataReader2", "netcdf"},LibraryDirectory=             
             "modelica://BuildingSystems/Utilities/LibrariesNcDataReader2/");

Advantage

• Independent of storage location of the BuildingSystems library
• Independent of Dymola's working directory

Disadvantage
This syntax is solver-dependent!
Working solvers are: Lsodar, Dassl, Euler, Rkfix2, Rkfix3 and Rkfix4.
Other solvers throw error messages corresponding to the NcDataReader.

This combination of solvers is mentioned two times within the Dymola documentation - each time in combination with Embedded Server settings. So far, we do no know if this has anything to do with the calls of IncludeDirectory or LibraryDirectory.

Using relative paths

Using relative paths to include the NcDataReader libraries and header files, the implementation of the examples from above change to

fileName = "./Climate/weather/WeatherDataNetcdf/Hamburg_meteonorm.nc";

and

annotation (Include="#include <ncDataReaderEA.h>", Library={"ncDataReader2", "netcdf"});

Advantages

• Independent of storage location of the BuildingSystems library
• Works with all provided solvers in Dymola

Disadvantage
Examples using this implementation will only be simulated without any error, if the working directory is set to the BuildingSystems location.

Using absolute paths

Using absolute paths to include the NcDataReader libraries and header files, the implementation of, the examples from above change to

fileName = "C:/Users/jmoeckel/Documents/Dymola/BuildingSystem/Climate/weather/WeatherDataNetcdf/Hamburg_meteonorm.nc";

and

annotation (Include="#include <C:/Users/jmoeckel/Documents/Dymola/BuildingSystem/Utilities/LibrariesNcDataReader2/ncDataReaderEA.h>",
           Library={"C:/Users/jmoeckel/Documents/Dymola/BuildingSystem/Utilities/LibrariesNcDataReader2/ncDataReader2",  
           "C:/Users/jmoeckel/Documents/Dymola/BuildingSystem/Utilities/LibrariesNcDataReader2/netcdf"});

Advantages

• Independent of Dymola's working directory
• Works with all provided solvers in Dymola

Disadvantage
Examples using this implementation will only be simulated without any error, if the location of the BuildingSystem library does not change (with respect to the host itsself). This is actually a great problem regarding the portability of the code.

Also note, that

• using the SaveTotal command will (of course) not the actual library files. If you want to distribute some models using the NcDataReader, make sure to additionally include these files.
• the above considerations are also true, if using BuildingSystems.Buildings.Ambiente. In this package a file with weatherdata could be referenced. Besides the reference, analogue to the NcDataReader files, the corresponding weatherfile needs to be manually provided.