For a project I have to read the Automatic Servo Tuning (AST) data and display the tuning data graphs for reporting on the machine. The XML is auto generated by the system and I am simply trying to decode the raw CDATA tag into an array of doubles. The XML says it is base85 encoded and I have tried online tools as well as nuget packages to decode the text.
So far I have only managed to translate into gibbrish. The forced binary to double BitConverter.ToDouble() method yields wildly fluctuating values which I know are not exactly correct.
How can I decode this data into a list of doubles? Below is a sample array from the XML file. This is supposed to be the sampling frequencies so I think they may be in a sorted order (if this helps).
<NumericArray satclassid="4" elementtype="double" format="base85" name="m_FrequencyVector" ver="4.8.5.0.3" env="1">
<unsigned_int name="m_length">1022</unsigned_int>
<raw name="m_pNumberArray">
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</NumericArray>
I believe the system used to generate this XML is SINUMERIK 840D, although I have not been successful in obtaining any programming guide by Siemens that helps understand the AST data.
Not surprisingly, I found the answer just a day after posting. Adding it here just for reference to others.
I found a Python repo on GitHub (link: Trace-Tools) which converts the base85 encoded data. It uses a custom character map from Siemens, which is why none of the standard converters worked.
For C#, I also had some issues with big-endian conversion but that is not be a difficult problem to solve.