GetJsonStringFromSymbolProperties

This method generates a corresponding JSON representation of PLC attributes on a symbol. In contrast to the AddJsonKeyPropertiesFromSymbol method, the result is not written to an instance of the function block FB_JsonSaxWriter, but to a string variable. The method receives as its input parameters the data type name of the symbol and a string variable that represents a list of the PLC attributes to be extracted, separated by a cross bar. The result is returned directly as the return value of the method.

The maximum size of the string returned by the method is 255 characters. With longer strings, the method will return a NULL string. In this case the method CopyJsonStringFromSymbolProperties() must be used.

Syntax

METHOD GetJsonStringFromSymbolProperties : STRING(255)
VAR_IN_OUT CONSTANT
  sDatatype   : STRING;
  sProperties : STRING;
END_VAR
VAR_OUTPUT
  hrErrorCode : HRESULT;
END_VAR

Return value

/ Inputs/Outputs

Outputs

Sample call:

sBuffer := fbJsonDataType.GetJsonStringFromSymbolProperties('ST_Values', 'Unit|DisplayName');