SOIS P&P input

1. SOIS P&P input

2. Introdcution • As part of the work to standardise onboard communication services, the CCSDS SOIS WG has recently delivered new draft standards on File and packet stores / message exchange; these standards are presently undergoing Agency review. • In parallel solid progress has been made in refining the communications architecture related to addressing and plug and play. • In particular, efforts are being made to align the SOIS work with existing developments, in particular IEEE 1451 and the AFRL SPA related standards released by the AAIA, with the intention of developing a CCSDS recommendation for the use of Electronic data sheets • In addition, ESA led activities such as SAVOIR are pushing ahead with industrial studies to further coordinate the provision of a reference avionics architecture with standard interfaces and building blocks • Finally, there are many TRP and GSTP research activities under release which are intended to support or implement the new building blocks • While all of the above can be considered as a successful demonstration of a coordinated approach, there is a real danger (with so many parallel activities), that efforts will diverge. • This presentation provides the outlook from a CCSDS SOIS viewpoint indicating how the work so far should be applied

3. SOIS motivation • The main motivation behind SOIS is reduce development costs and risks associated with interconnecting elements of the flight avionics • The SOIS approach is to define a set of communication services at both application and subnetwork layers. These services are supplemented by protocols developed either by ECSS or CCSDS • The approach provides a common interface to applications independent of the topology of and specific details of the underlying hardware • Onboard subnets provide a common set of services regardless of the physical media and associated data link protocol • Data link protocols are fully specified in accordance with the SOIS services, thus removing the need for ad-hoc development and mission specific testing

4. CCSDS SOIS Status • The completion of the CCSDS SOIS effort to standardise onboard communications services and protocols is now in sight with many standards already released • Efforts are now concentrating on standardising the interfaces to onboard sensors and actuators both at the communication and functional levels • At the communication level, the existing IEEE1451 standards for smart transducers is presently the most likely candidate including the use of the Transducer electronic data sheet (EDS) • For the functional interface, consideration is being given align with the AFRL developed Extended TEDS (X-TEDS). This is being used as part of the SPA initiative for rapid spacecraft development and is undergoing standardisation by the AAIA • The architecture supporting the above is described in an updated version of the SOIS Green book (Http ref xxx)

5. Standards Availability Application Support Layer CMD & Data Acquisition Services Time Access Service File & packet Store Services Message Transfer Service Device Enumeration Service 3 standards completed Subnetwork Layer Packet Service Memory Access Service Synchronisation Service Device Discovery Service Test Service ECSS Datalink Standards All standards completed Milbus Spacewire Canbus Serial In accordance with SOIS services Underway, completion 2011 Planned completion 2012

6. SOIS P&P architecture

7. SOIS P&P architecture

8. Use of Electronic data sheets

9. IEEE 1451 standards

10. IEEE 1451 – “RTU Architecture”

11. 1451 – use of TEDs

12. RTU as element of P/F Avionics: P/L MMU P/L SpW, HSSL,SpF MIL-STD-1553B, CAN, SpW P/L Bus CDMU ECSS-E-ST-50-13C ECSS-E-ST-50-12C,… ECSS-E-ST-50-15dr MIL-STD-1553B CAN RS-422 SpW ECSS-E-ST-50-14C ECSS for digital sensor busses RTU P/F Bus RTU2015 PCU/PCDU Sensors & Actuators (T, AOCS, Propulsion, …) Power Bus Load

13. RTU : possible configurations

14. Questions for SOIS WG • IEEE1451 use the same architecture as the proposed ESA RTU. 1451 uses XTEDS for devices but presents a standard API for access over the user network – How does this fit with the SOIS P&P architecture, in particular the DAS and DVS • ESA is also standardising the use of CANBus as a primary onboard bus. CANBus has its own (text based) EDS – how does this fit with the SOIS P&P architecture? (important as use of CAN will force equipment suppliers to provide EDS’s) • There are several “object dictionaries” (1451, CAN, XTEDS) available – how (should we) do we rationalise these into a single view and document? • Our diagrams to not yet reflect the use of a device specific protocol to support the device access service – propose this should be identified/specified as this will be needed e.g. for standard access to an RTU • The SPA guidebook contains a section on SOIS – is everybody happy that the text correctly reflects the comparison with SPA? • The Green book has been updated, are there still actions and updates and what are the plans for the review and release? • Although we made a great step forwards at the last meeting and reflected the results in the Green book, I’m concerned that the GB text is a little ‘academic’ and would benefit from a practical example to supplement the layered model – comments anyone?