The following section describes the two architectures that are defined by this specification. The Object models defined in other sections of this specification are affected by these architectures (see Figure 7.)
Figure 7 - Architecture Overview
This narrative and associated architecture drawing are intended to identify and represent this interface in the majority of typical system implementations. It is not intended to mandate the detailed architecture of a DCS vendor or SPCS vendor’s control system, nor is it intended to suggest or exclude a particular contracting / commercial strategy. This simplified version of the MDIS interface was used to facilitate development of the data objects and to define the data content between the DCS and SPCS vendor’s system.
Two major architectures, “Integrated” or “Interfaced”, are typically used throughout the industry and the choice will typically be decided by the Operating Company. Since the control aspects of the subsea system can be accomplished by both the DCS system or by the subsea system, the actual interface between the two systems may be different. In the Integrated architecture (Case 1), the controls system is an integrated system where all control is performed by the DCS vendor’s hardware and the standard needs to support communication of all information between the subsea gateway and the DCS control system. This enables a single HMI (or set of HMIs) to control and monitor platform and subsea operations. In the Interfaced architecture (Case 2), the SPCS vendor provides the controls for the subsea aspects of the system and the DCS system is used for monitoring and set point control purposes of the subsea system, along with topside controls. The MDIS InformationModel is able to adapt to both of these architectures.