Download - SOIS P&P input
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SOIS P&P input
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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
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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
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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)
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Standards Availability
CMD & DataAcquisitionServices
Time AccessService
File & packet Store
Services
Message TransferService
DeviceEnumeration
Service
Packet Service
MemoryAccessService
SynchronisationService
DeviceDiscoveryService
Test Service
ApplicationSupport Layer
Subnetwork Layer
All standards completed
3 standards completed
In accordance with SOIS services
ECSS DatalinkStandards Milbus Spacewire Canbus Serial
Underway, completion 2011 Planned completion
2012
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SOIS P&P architecture
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Device VirtualisationService
Device VirtualisationService
Device AccessService
Device AccessService
SubnetworkPacket or Memory
Access Service
SubnetworkPacket or Memory
Access Service
SubnetworkProtocol
Implementations
SubnetworkProtocol
Implementations
SOIS
HardwareDevice
HardwareDevice
SubnetworkImplementation
Hardware
Applications
ApplicationApplication
Physical Device
Interface to subnetwork service
Provides acquisition of device vales
Permits device commanding
Manages underlying device modes
Handles device protocol
Standardises device values
Standardises device semantics
Provides all necessary operations
Standard interface
Subnetwork service implementation
SOIS P&P architecture
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Device Electronic Datasheet
(SOIS)
Device Electronic Datasheet
(IEEE 1451)
TranslationDVS and DAS
Implementations
Auto-Coding
Virtual DeviceInterface
Definitions(xTEDS)
Extract and Publish
If Device has IEEE 1451 Datasheet
If Device Datasheet is Complete and Device is
Standard Type
Or Auto-Configuration
Use of Electronic data sheets
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IEEE 1451 standards
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IEEE 1451 – “RTU Architecture”
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1451 – use of TEDs
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RTU as element of P/F Avionics:
CDMU
RTURTU2015
P/F Bus
P/L Bus
MIL-STD-1553BCANRS-422SpW
ECSS-E-ST-50-13CECSS-E-ST-50-12C,…ECSS-E-ST-50-15dr
Sensors &Actuators(T, AOCS,Propulsion, …)
ECSS-E-ST-50-14CECSS for digital sensor busses
MIL-STD-1553B, CAN, SpW
MMU P/LP/LSpW, HSSL,SpF
PCU/PCDU
Power Bus
Load
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RTU : possible configurations
OBC/CDMU/SMU
RTU2015 #2
Backplane
DC/DC Controller
SpWRTC
SpWRouter
RTU2015 #1
Backplane
DC/DC Controller
FPGAWith
CCIP/1553/RS422 I/F
uControllerWith CAN/
1553/RS422 I/F
HK
SLAVE
MOD
SADM
CTRL
MOD
HK
SLAVE
MOD
DigSERIAL
Bus
MOD
WIRELESS
DataCollec.
MOD.
CAN/1553B/RS422
SpW
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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?