In accordance with the diagram above, we obtain the following sequence of requests for data acquisition and their transfer:
- object of the SCADA-system sends the value request to the object of the parameter attribute DAQParamAttribute::getVal();
- object of the parameter attribute, receiving the request, sends it to the data source HardwarePLC::valueRequest();
- data source after processing the request returns the result;
- object of the parameter attribute, receiving the result, returns its to the SCADA-system object.