Extended data types in MindSphere

Basic idea

Extended data types, i.e. data types that have complex internal structure and may require significant memory (> 1 Megabyte), are stored in IOT in the following way:

  • Only meta information about data is stored in a time series record

  • Meta information contains a link to the place, where the data is stored. File API is used to store data in files at an asset

  • Meta information can also contain data that can be used for filtering

Path

Extended data are stored at an asset under the following path:

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/mceaextendeddata/{aspect_name}/{variable_name}/{timestamp_linux_epoch_in_seconds}

The maximal length of the path must be <= 100 according to File Service API. It is automatically fulfilled for X-Tools Professional, where there is a limit on aspect and variable name = 30 characters. 

Data format

Meta information is stored in the format below as STRING or BIG_STRING depending on its length. The field "details" is optional.

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{

"typeId": "<type_id>",

"version": "<type_version>",

"path": "<file path>"

"details":

{

<any further useful meta information that can be used for filtering>

}

}

Data output format

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[

{

"<variable_name>":

{

"typeId": "<type_id>",

"version": "<type-version>",

"path": <file_path>"

"details":

{

<any further useful meta information that can be used for filterings>

}

}

"_time": "<timestamp>",

},

...

]

Example: frequency spectrum with amplitudes and phases

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{

"typeId": "mcea.sprectrum.frequencyamplitudephases",

"version": "1.0.0",

"link": "Pool-Spectrum/Pool_spectrum"

"details":

{

"min": 0;

"max": 1000,

"fftBins": 1024

}

}

Example: frequency spectrum with amplitudes

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{

"typeId": "mcea.sprectrum.frequencyamplitudes",

"version": "1.0.0",

"link": "Pool-Spectrum/Pool_spectrum"

"details":

{

"min": 0;

"max": 1000,

"fftBins": 1024

}

}

Example: complex spectrum

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{

"typeId": "mcea.sprectrum.complex",

"version": "1.0.0",

"link": "Pool-Spectrum/Pool_spectrum"

"details":

{

"min": 0;

"max": 1000,

"fftBins": 1024

}

}