OpenSCADA provides for the possibility of such unification through affiliation with PLC. Such affinity can only be provided for PLCs that are completely open, they have open-source software installed, and so you can install OpenSCADA as a PLC execution environment. As an execution environment, OpenSCADA can provide PLC data also by the standard protocols such as ModBus, and to obtain these data directly and without any action on them on the side of the SCADA system, there is the module DAQGate provided, which in fact brings these models together. That is the PLC-programmer, which is a SCADA-programmer also, forms a PLC data model, and at the SCADA-level it is already used as a ready-made, which completely removes the stage and works on obtaining, processing and forming the data model of the SCADA-system. Moreover:
- the discrepancy between PLC and SCADA data models is eliminated when they are changed;
- the configuration data logically and exclusively is stored on the PLC to which they relate;
- violations and other messages are generated on the primary source — PLC, and messages of the intrusions — actions of the operator, are also sent to the PLC;
- provides for a mechanism for storing archive-history on the PLC both fully and as part of the compensation for loss of communication with the SCADA, especially for bad and wireless communications.