Conversion Methods
Conversion methods enable you to use data group elements within a data group to convert data from a data source into a different format. Sometimes source data is accessed directly and sometimes by reference. Unlike reference methods, however, conversion methods perform server-side conversions. Conversion method data is stored to the Device Definition Service (DDS), but reference method data is not.
The following topics list and explain common ways you can use conversion methods to perform conversions. You can employ conversion methods to customize templates to communicate with a field device in a way that best suits your needs. For example, a field device might return a date-time value that is represented in an uncommon format, but you want to display the value in a common format. A conversion method could be defined in the template that converts the value from an uncommon format to a common one.
There are two conversion method types. One uses the attribute cvtF and the other uses the attribute cvtRef.
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The cvtF conversion method type is usually EIE specific and directly converts source data.
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The cvtRef conversion method type is Modbus protocol specific, which means that it is available for use with any Modbus or Modbus-derived EIE. The cvtRef method type is currently only used to convert source date-time values into the Microsoft standard date-time format (COleDateTime) from a referenced date-time format.
For information about device template file elements and attributes, see Elements and Attributes.
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