The control system can be in form of DCS, PLC, RTU and SCADA, PLC and SCADA, of just simple micro controller devices to control simple process.

The complexity of the control system is depending on the object that will be controlled. More complex and massive the controlled objects scope then it should have more “high end” control system platform.

Such as the PLC, it can be used as the control system framework for some application, but may be not too wise to implement it to cover the more complex control object environment such as the production plant and platform or refinery process, since these type of object will need more capability and capacity of control system framework. The DCS will be more proper to be implemented for this type of application.

The integration of the control system as the layer 1 and 2 in the IEC 62443-1 model with the layer 3 and enterprise network can be deployed by using SCADA or Historian framework, or it can also interconnected by DMC system in the top layer (layer 3) as the top buffer interface of the DCS before connected to the enterprise network.

Nowadays, most of the new-implemented control system will have interconnection (directly or indirectly) to the enterprise network for the integrated production operations performance monitoring, reporting, maintenance, planning and optimization. The most important thing to be considered by having this interconnection between control system domain with enterprise domain is the security assurance, which should be engineering properly in order to protect the critical asset (the control system and production operations entities, including people & environment) from the external threat (L4 entities) and unidentified hacker.