CopyJsonStringFromSymbolProperties
![CopyJsonStringFromSymbolProperties 1:](Images/jpg/13478374923__Web.jpg)
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 method copies this JSON representation into a variable of the data type STRING, which can be of any length. The method returns the length of the string (including null termination). If the destination buffer is too small, it is emptied by a null termination and returned as length 0.
Syntax
METHOD CopyJsonStringFromSymbolProperties : UDINT
VAR_INPUT
nDoc : UDINT;
END_VAR
VAR_IN_OUT CONSTANT
pDoc : STRING;
sDatatype : STRING;
sProperties : STRING;
END_VAR
VAR_OUTPUT
hrErrorCode : HRESULT;
END_VAR
Return value
Name | Type |
---|---|
CopyJsonStringFromSymbolProperties | UDINT |
Inputs
Name | Type |
---|---|
nDoc | UDINT |
/
Inputs/Outputs
Name | Type |
---|---|
pDoc | STRING |
sDatatype | STRING |
sProperties | STRING |
Outputs
Name | Type |
---|---|
hrErrorCode | HRESULT |
Sample call:
nLen := fbJsonDataType.CopyJsonStringFromSymbolProperties('ST_Test','Unit|DisplayName',sString,SIZEOF(sString));