Established in 2003, the SIIS Joint Industry Project has been looking to standardise and produce a Recommended Practice (RP) document for three communication protocols between Subsea Control Modules (SCMs) and subsea sensors.

SIIS has 25+ member companies consisting of Controls System Suppliers, Instrument Suppliers and Operators who work together defining standards for Instrument Interfaces.

• Level 1 – Analogue Devices:  These devices are 4-20 mA sensors, 2 wire loop powered analogue output sensing devices. RP complete
• Level 2 – Digital Serial Devices:  These devices are relatively complex sensors or instruments which have serial digital connections to the control system in a star connection style. They can also include downloadable characteristics and, most importantly, described as having ‘Open Standard’ characteristics. These can be multi measurand devices that can be distributed on a multi-dropped topology. The communication protocol uses CANopen (CiA 443) over an ISO 11898-3 (fault tolerant) physical layer. RP complete
• Level 3 – Ethernet TCP/ IP Devices:  These devices are used with Intelligent Seabed Devices (ISD) where direct communication access is required between the ISD Surface Application Systems (ISAS) and the ISD. It is not usually required for the Subsea Production control System to know the application layer protocols (Layer 7) in use by the devices. This device interface may also be used for sensors requiring bulk data transfer. The communication protocol is TCP/IP over Ethernet (ISO/IEC 8802.3).  RP complete