User defined onRead and onWrite functions

Every parameter has three function pointers to allo user defined actions on read, write and setToDefault. This is useful for e.g.

• The parametervalue is not stored in a variable, but in a structure.
• After write of filter-settings the integrator must be reinitialized.
• The paramtervalue must be scaled before display.
• The parameter should perform an action on write.

If no customized action is neccessary, the default action must be linked. This default action is dependant of the datatype of the parameter. For every useable datatype a default action is defined:

• signed char: ReadFunction_STD_I8, WriteFunction_STD_I8, SetToDefaultFunction_STD_I8
• unsigned char: ReadFunction_STD_U8, WriteFunction_STD_U8, SetToDefaultFunction_STD_U8
• signed word: ReadFunction_STD_I16, WriteFunction_STD_I16, SetToDefaultFunction_STD_I16
• unsigned word: ReadFunction_STD_U16, WriteFunction_STD_U16, SetToDefaultFunction_STD_U16
• signed int: ReadFunction_STD_I32, WriteFunction_STD_I32, SetToDefaultFunction_STD_I32
• unsigned int: ReadFunction_STD_U32, WriteFunction_STD_U32, SetToDefaultFunction_STD_U32
• signed long: ReadFunction_STD_I64, WriteFunction_STD_I64, SetToDefaultFunction_STD_I64
• unsigned long: ReadFunction_STD_U64, WriteFunction_STD_U64, SetToDefaultFunction_STD_U64
• float: ReadFunction_STD_F32, WriteFunction_STD_F32, SetToDefaultFunction_STD_F32
• string: ReadFunction_STD_STR, WriteFunction_STD_STR, SetToDefaultFunction_STD_STR

Read and write functions have as return value the number of processed bytes. In case of 0 as return value an error occured.

Example for a onWrite Function

int32_t WriteFunction_Run(Parameter* ptThis, uint16_t ui16SubId, void* pData, int32_t ui32MaxCount, uint32_t ui32Offset, ParameterAccessSource tAccessSource, uint8_t ui8AccessLevel)
{
    uint8_t val;
    
    if (IsValidForWrite(ptThis, ui16SubId, pData, ui32MaxCount, ui32Offset, tAccessSource, ui8AccessLevel) == false)
        return 0;
 
    val = ((uint8_t*)pData)[0];
   
    switch(val) 
    {
        case 0:
            Stop();     
            break;
        case 1:
            if (IsRunning()) 
                return 0;           
            Run();
            break;
        default:
            return 0;
    }
 
    return GetDataTypeSize(TYPE_uint8);
}

If the written value is 1, the device is started. If 0 the device stopps. The value is not written ot a variable, only the action is performed. In the same parameter the state of the device is read with this onRead function:

int32_t ReadFunction_Run(Parameter* ptThis, uint16_t ui16SubId, void* pData, int32_t ui32MaxCount, uint32_t ui32Offset, ParameterAccessSource tAccessSource, uint8_t ui8AccessLevel)
{
    if (IsValidForRead(ptThis, ui16SubId, pData, ui32MaxCount, ui32Offset, tAccessSource, ui8AccessLevel) == false)
        return 0;
 
    if (get_state() & RUN_FLAG)
    {
        ((uint8_t*)pData)[0] = 1;
    }
    else
    {
        ((uint8_t*)pData)[0] = 0;
    }
    
    return GetDataTypeSize(TYPE_uint8);
}