Physical architecture, defined in Section 5.1, should be specified. The location of the following minimum set of functionality, in the DCS or SPCS, is dependent on physical and “Operating Company” requirements and should be clearly specified prior to project execution:

  • Data Arbitration
  • Communication Channel Selection
  • SEM Control Selection
  • Process Interlocks
  • Product Interlocks
  • Shutdown Sequences
  • Automated Control Sequences
  • Valve Status Validation
  • Choke Position Validation
  • Interfacing with the HPU
  • Interfacing with the topside chemical injection system
  • Validation of Valve Profiles / Signatures

While functional logic has been prescribed by MDIS; implementation of specific functionality is not mandatory and should be specified on a project basis. As a minimum any MDIS implementation should ensure exchange of all required information required to safely line up, start up, operate and shutdown subsea equipment.

Interfaces with external interfaces with other third-party systems (i.e. historians) and external interfaces between SPCS and DCS for use other than for control and monitoring of subsea equipment are not specified through the use of the MDIS OPC UA Companion Specification and should be specified on a project basis.