SOIS and Software Reference
Architecture
F. Torelli
DASIA 2011 - Malta
17/05/2011
ESA UNCLASSIFIED – For Official Use
Outline
1. SOIS architecture and services
2. SOIS architecture and Avionics System Reference
Architecture
3. Impacts to the design of flight software
4. Status of SOIS publications and related developments
5. Conclusions
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 2
ESA UNCLASSIFIED – For Official Use
SOIS architecture and services
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 3
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CCSDS SOIS Architecture
SOIS provides an abstraction of the functionality of the spacecraft units in a
layered fashion.
Mission
Specific
Applications
Application
Layer
Communication Management
Application
Support Layer CMD & Data
Acquisition
Services
Transfer
Layer
Time
Access
Service
File &
Packet Store
Services
Standard Services
Message
Transfer
Service
Device
Enumeration
Service
Transport Protocol
Standard Services
Network Protocol
Subnetwork
Layer
Memory
Access
Service
Packet
Service
Synchronisation
Service
Device
Discovery
Service
Test
Service
Datalink Convergence Protocols
Milbus
SpaceWire
CAN
Wireless
ECSS Standard
Protocols
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 4
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Sub-Network Services
–
abstract from the physical location
(within the spacecraft) of the unit to
be accessed
Communication Management
Sub-network services:
Mission
Specific
Applications
Application
Layer
Application
Support Layer CMD & Data
Acquisition
Services
Transfer
Layer
Time
Access
Service
File &
Packet Store
Services
Network Protocol
Subnetwork
Layer
Memory
Access
Service
Packet
Service
Synchronisation
Service
Device
Discovery
Service
Test
Service
Datalink Convergence Protocols
abstract from the datalink protocol required
by a specific communication media to access a unit
–
abstract from time constrains strictly related to the specific
communication media used to access a unit
–
abstract from the addressing scheme required by a specific
communication media to identify a unit.
ESA UNCLASSIFIED – For Official Use
Device
Enumeration
Service
Transport Protocol
–
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 5
Message
Transfer
Service
Milbus
SpaceWire
CAN
Wireless
Command & Data Acquisition
Services
–
–
abstract from the protocol required to control
the device (Device Access Service)
Communication Management
Command & Data Acquisition services:
Mission
Specific
Applications
Application
Layer
Application
Support Layer CMD & Data
Acquisition
Services
Transfer
Layer
Time
Access
Service
File &
Packet Store
Services
Message
Transfer
Service
Device
Enumeration
Service
Transport Protocol
Network Protocol
Subnetwork
Layer
abstract from the type of communication
service (i.e. memory access, packet-base)
required to access the device (Device Access Service)
Memory
Access
Service
Packet
Service
Synchronisation
Service
Device
Discovery
Service
Test
Service
Datalink Convergence Protocols
Milbus
SpaceWire
CAN
Wireless
–
abstract from time constrains strictly related to the device specific
access protocol (Device Access Service)
–
decouple device physical access from device data consumption by
the applications (Device Data Pooling Service)
–
add ontology to the raw command and data information related to
devices (Device Virtualisation Service)
–
provide a uniform interface for each class of devices, independent
from their actual implementation (Device Virtualisation Service).
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 6
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Other Application Support Services
–
abstracts from the mechanisms required
to access the on-board reference time and
to handle time alarms.
Message Transfer Service:
–
Communication Management
Time Access Service:
Mission
Specific
Applications
Application
Layer
Application
Support Layer CMD & Data
Acquisition
Services
Transfer
Layer
Time
Access
Service
File &
Packet Store
Services
Message
Transfer
Service
Device
Enumeration
Service
Transport Protocol
Network Protocol
Subnetwork
Layer
Memory
Access
Service
Packet
Service
Device
Discovery
Service
Synchronisation
Service
Test
Service
Datalink Convergence Protocols
Milbus
SpaceWire
CAN
Wireless
provides a high level and uniform mechanism to communicate
between software applications within the spacecraft.
File and Packet Store Service:
–
provides a standardised interface to mass memory file and packet
stores
–
abstracts from the implementation details related to the mass
memory file systems.
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 7
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Plug and Play Services
–
–
–
provide mechanisms to discovery and
configure devices connected to a sub-network
provide mechanisms to handle units
redundancy
Communication Management
Plug and Play Services:
Mission
Specific
Applications
Application
Layer
Application
Support Layer CMD & Data
Acquisition
Services
Transfer
Layer
Time
Access
Service
File &
Packet Store
Services
Message
Transfer
Service
Transport Protocol
Network Protocol
Subnetwork
Layer
Memory
Access
Service
Packet
Service
Synchronisation
Service
Device
Discovery
Service
ESA UNCLASSIFIED – For Official Use
Test
Service
Datalink Convergence Protocols
Milbus
SpaceWire
CAN
provide the means to interpret
the content of Electronic Data Sheets and to configure the other
services accordingly (C&DA).
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 8
Device
Enumeration
Service
Wireless
Protocols supporting the Services
The services are complemented by protocols
Sub-Network Protocols:
Communication Management
implement the functionality specified by SOIS.
Mission
Specific
Applications
Application
Layer
Application
Support Layer CMD & Data
Acquisition
Services
Transfer
Layer
Time
Access
Service
File &
Packet Store
Services
Message
Transfer
Service
TBD
AMS
Device
Enumeration
Service
Transport Protocol
Network Protocol
Subnetwork
Layer
Memory
Access
Service
Packet
Service
Synchronisation
Service
Device
Discovery
Service
Test
Service
Datalink Convergence Protocols
–
Mil-Std-1553, ECSS-E-ST-50-13C
–
CAN, ECSS-E-ST-50-15C draft
–
Spacewire, ECSS-E-ST-50-52 (RMAP), ECSS-E-ST-50-XX (SpW-D)
Milbus
SpaceWire
CAN
Wireless
Message Transfer Service Protocol:
–
Asynchronous Message Service, CCSDS 735.1-B-0
File and Packet Store Service Protocols:
–
Network File Access, Network Packet Access and Remote Block Storage
Protocols need to be standardised
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 9
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SOIS and Avionics System Reference
Architecture
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 10
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Avionics System Reference
Architecture
Application BB (mission
dependent)
Satellite Conf
and Eqpt
Mgmt
Central
FDIR
SSMM Mgmt
AOCS
Plan/
Autonomy
Framework
Thermal
System mode
mgmt
Power
OBT Mgmt
P/L Manager
Software bus
Execution platform
PUS specific
Abstract component
services
PUS and
MTL
services
OBCP
interpreter
PUS
monitoring
Avionics
Equipment
virtual
devices
=SOIS DVS
TM/TC
Security
Unit
SSMM
Solid
State
Mass
Memory
File/
Compress
/
Encrypt
SOIS
Layers
Libraries:
mathematical,
etc.
RS422
Context
Mgmt
On-board
time
=SOIS TAS
Connector
services
Communication
services
addressing
physical
distribution across
nodes
= SOIS MTS
SOIS Subnetwork layer (1553, CAN, SpW)
(including HDSW)
OBC Hardware
CAN
Component
services
SpW
RAM
EEPROM
Standardized
devices
Intelligent
devices
BSP
OBTimer
DSP
Boot
PROM
SGM
RTU/
Intelligent IO
HW
watchdo
g
SOIS
Layers
Onboard Communications H/W
(e.g. MIL-STD-1553B, SpaceWire, CAN RS422)
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 11
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Legacy
devices
RTOS
Sensor
and
actuators
CPU/
NGmP
MIL-1553
Container
services
Payloads &
Instruments
Space
Linux
ADCs / DACs
Digital
Sensorbus
SOIS
Layers
Payload
Compute
r
SOIS in the Avionics System
Reference Architecture 1/2
On-Board Computer (OBC):
The full set of SOIS services is intended for implementation in the OBC
flight software as part of the Execution Platform building block.
Other Equipments:
A reduced subset of SOIS service is foreseen for the external units
such as RTUs, Solid State Mass Memory, Intelligent Sensors and
Actuators, Payloads in accordance with their functionality and
supported features.
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 12
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SOIS in the Avionics System
Reference Architecture 2/2
Application BB (mission dependent)
Mission
Specific
Applications
Application
Layer
AOCS
Central FDIR
SSMM Mgmt
Communication Management
Plan/ Autonomy
Framework
Satellite Conf
and Eqpt Mgmt
Thermal
System mode
mgmt
Power
OBT Mgmt
P/L Manager
Software bus
Application
Support Layer CMD & Data
Acquisition
Services
Transfer
Layer
OBCP
interpreter
PUS
monitoring
Avionics
Equipment
virtual
devices
=SOIS DVS
TM/TC
Security
Unit
SSMM
Solid
State
Mass
Memory
File/
Compress
/
Encrypt
SOIS
Layers
Libraries:
mathematical,
etc.
Component
services
Context
Mgmt
On-board
time
=SOIS TAS
Connector
services
Communication
services
addressing
physical
distribution across
nodes
= SOIS MTS
SOIS Subnetwork layer (1553, CAN, SpW)
(including HDSW)
OBC Hardware
Device
Enumeration
Service
Network Protocol
Memory
Access
Service
Packet
Service
Synchronisation
Service
Device
Discovery
Service
Milbus
Container
services
Standardized
devices
SpaceWire
CAN
Test
Service
CPU/
NGmP
Legacy
devices
Intelligent
devices
BSP
OBTimer
MIL-1553
RAM
DSP
RS422
SpW
EEPROM
Boot
PROM
Wireless
RTOS
Sensor
and
actuators
CAN
SGM
RTU/
Intelligent IO
HW
wdog
SOIS
Layers
Onboard Communications H/W
(e.g. MIL-STD-1553B, SpaceWire, CAN RS422)
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 13
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Message
Transfer
Service
Datalink Convergence Protocols
Abstract component
services
PUS and
MTL
services
File &
Packet Store
Services
Transport Protocol
Subnetwork
Layer
Execution platform
PUS specific
Time
Access
Service
Space
Linux
Payload
Compute
r
ADCs / DACs
Digital
Sensorbus
Payloads &
Instruments
SOIS
Layers
SOIS
Layers
Impacts to the design of flight software
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 14
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Traditional Flight Software
In a traditional flight SW system, AOCS and equipment time requirements defining
the bus schedule also drive the flight SW architecture and the SW tasks schedule.
Bus and ASW Time Domain Mixed
The system is designed as a “monolithic” entity tailored for the specific
mission.
Payload 2
Manager
OBCP
Interpreter
MTL
Manager
TC
Manager
AOCS
Processing
Payload 1
Manager
HK TM
Processing
HK TM
Processing
MilBus
Manager
MilBus
Manager
MilBus
Manager
AOCS
Acquisitions
Payload 1
Acquisitions
Minor Frame 0
(125 msec)
Minor Frame 1
(125 msec)
MTL
Manager
EEPROM
Manager
Science TM
Processing
Mass
Memory
Monitoring
Mode
Manager
MilBus
Manager
MilBus
Manager
MilBus
Manager
Payload 2
Commanding
AOCS
Commanding
Large Data
Transfer
Payload 2
Acquisitions
Minor Frame 2
(125 msec)
Minor Frame 3
(125 msec)
Minor Frame 6
(125 msec)
Minor Frame 7
(125 msec)
HK TM
Processing
…
Major Frame (1 sec)
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 15
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Scrubbing
t
Motivations for an Improvement
Such a synchronous schedule works to accomplish relatively simple
mission requirements, however:
1. to improve the development process,
2. to accommodate more functions on board,
3. to enable new emerging technologies (e.g. multi-core processors,
time and space partitioning, increased autonomy)
It is advisable to move towards an avionics architecture based on
composable building blocks where functional and timing
requirements, if possible, are addressed at component level
(separation of concerns).
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 16
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Proposed Way Forward
SOIS Services:
The introduction of the previously mentioned SOIS standardised
services supports this approach allowing to decouple the functional and
timing requirements strictly related to the communication protocols
from the ones related to the device access protocols and again from
the ones related to the applications algorithms.
These concepts will be briefly discussed for:
-
Sub-Network Services
-
Command & Data Acquisition Services
-
Message Transfer Service.
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 17
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Sub-Network Services
Characterisation
Low level communication req. can be captured in the sub-network layer to
define the bus profile and to expose to the upper layers of the flight software
functional and non-functional attributes of the services primitives.
AOCS
Algorithm
Duration
AOCS
Frequency
Sensor
Sensor
Sensor
Max
Max
Max
Latency
Latency
Latency
Command
Command
Command
Accuracy
Accuracy
Accuracy
Service Time and
Functional Characterisation
Sub-Network Service Primitives
Bus Profile
Bus Protocol
Actuators
Actuators
Actuators
Access
Access
Access
Time
Time
Time
Sensor
Sensor
Sensor
Access
Access
Access
Time
Time
Time
Equipmen
Equipmen
Equip.
t Physical
t Physical
Physical
Address
Address
Address
Bus
Bandwidth
Allocation
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 18
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Traffic Scenario for the
Nodes
Command & Data Acquisition
Services Characterisation
The requirements related to the mechanisms to access the on-board
devices can also be isolated within the C&DA services group, mainly in
DAS and DVS.
Calib.
Curves
Electronic
Data
Sheet
Common
Data
Dictionary
Sub-Net
Service
Timing
Device
Required
Interface
Engineering
Data Format
Raw
Data
Format
Device
Access
Req.
Service Time and Functional
Characterisation
Device
Enumeration
Service
Device
Virtualisation
Service
Device
Access
Service
Raw Command/Acquisition
Sequence
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 19
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The services can be
automatically
configured and
instantiated during
the design phase
based on the
description of the EDS
and provide a well
characterised and
standardised
interface.
Message Transfer Service
Characterisation
In the Avionics System Reference Architecture, the Software Bus entity is in
charge to support the communication between applications and SW components.
Although the Software Bus can be implemented with different mechanisms, it is
clear that the SOIS MTS provides the needed infrastructure.
PUS
Services
APID
Definition
Tasks
Deadlines
Service Time and Functional
Characterisation
Message Transfer Service Primitives
Asynchronous Message Transfer Service
Protocol
External
Nodes
Routing
TM/TC
Formats
Sub-Net
Service
Timing
Registration Table
Message Traffic with Local
and Remote SW Entities
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 20
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Flight Software using SOIS Services
ASW Time Domain
ASW tasks schedule and I/O schedule are now related each others only due to the
AOCS dependencies and the I/O operations are represented in terms of services
(SOIS request & indication, time events).
Components can be designed independently according to the functional
and non-functional attributes of the interfaces.
Payload 2
Manager
TC
Manager
OBCP
Interpreter
SOIS
C&DA
AOCS
MTL Manager
SOIS
C&DA
SOIS
FPSS
HK TM Processing
Bus Time
Domain
Payload 1
Manager
Science TM
Processing
EEPROM
Manager
Scrubbing
Monitoring
Mode
Manager
SOIS SubNetwork
SOIS SubNetwork
SOIS SubNetwork
SOIS SubNetwork
SOIS SubNetwork
SOIS SubNetwork
AOCS
Acquisitions
Payload 1
Acquisitions
Payload 2
Commanding
AOCS
Commanding
Large Data
Transfer
Payload 2
Acquisitions
Minor Frame 0
(125 msec)
Minor Frame 1
(125 msec)
Minor Frame 2
(125 msec)
Minor Frame 3
(125 msec)
Minor Frame 6
(125 msec)
Minor Frame 7
(125 msec)
…
Major Frame (1 sec)
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 21
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t
Improvements to Flight Software
Some of the beneficial effects of the introduction of
standard services:
–
the possibility to develop and analyse the software
applications/components based on clear interfaces
–
the possibility to deploy some of the applications on a different
processing core or partition without impacting the design of the
avionics system
–
the possibility to exchange software/hardware components
(e.g. sub-network services) with minimal impacts to the overall
design.
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 22
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Status of SOIS publications and related
developments
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 23
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Status of SOIS documentation
SOIS Sub-Network Services:
–
published in 2009 and are currently used to drive new and upgraded
ECSS protocols for CAN and Spacewire.
SOIS Application Support Services:
–
Time Access Service published in 2011
–
File and Packet Store Service and Message Transfer Service are
currently under Agency review and will be published in 2011
–
C&DA services are planned for 2011/2012
CCSDS SOIS work is now concentrated on:
–
the refinement of the communication architecture, particularly in
terms of addressing and the provision of software APIs
–
The use of electronic data sheets to automate the process of
interface definition and integration (C&DA and DES)
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 24
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Present and Future Developments
Ongoing activities supporting standardisation:
–
–
–
–
–
–
A SOIS prototype is presently being prepared by SciSys (UK) in collaboration with ASTRIUM (F).
This will result in an upgraded RASTA system at ESTEC and a published set of IPR free API’s.
A prototype of the CCSDS file transfer protocol (CFDP) mapped to an implementation of the SOIS
file and packet store services is being prepared by Spacebel (B). This will also result in an
upgraded RASTA system.
Packet Store Services have also implemented by Scisys (UK) in the frame of the MARC project.
An ECSS standard for CAN Bus is under preparation. This is being driven by the Exomars program
and will result in an IP core compatible with SOIS sub-network services.
A SOIS/ECSS software component for Mil1553 Bus Controller has been developed by RUAG
(S) and its counter part for Remote Terminal Units is being implemented. These software building
blocks are produced in compliance with the flight software ECSS standards and validated on the
RUAG’s flight hardware platforms (Tiger and Panther boards).
An alternative SOIS/ECSS sub-network services implementation for Mil1553 Bus Controller
have been developed by Terma (DK) and integrated in the Avionics System Test Bench at ESA.
On 2011 the following additional activities are planned:
–
–
–
A TRP activity exploring the use of Electronic Data Sheets.
A TRP activity demonstrating Plug and Play techniques.
A TRP activity proving an end-to-end test-bed for the evaluation of file based communication
and operations.
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 25
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Conclusions
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 26
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Conclusions 1/2
–
The key characteristics of the SOIS services architecture have been presented.
–
It has been shown that some of the essential features of the Execution
Platform in the Avionics System Reference Architecture can be specified
and implemented using the SOIS services.
Execution platform
PUS specific
PUS and
MTL
services
Abstract
component
services
OBCP
interpreter
PUS
monitoring
SOIS C&DA
Component
services
Connector
services
Context
Mgmt
SOIS MTS
On-board
time
=SOIS TAS
Container
services
Reg
Table
RTOS
EDS
Libraries:
mathematical,
etc.
Bus Profile
SOIS Sub-Network
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 27
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BSP
Conclusions 2/2
–
Some services have been discussed in the context of the avionics
and flight software design phase, here the flexibility given by these
services demonstrates to be very beneficial as it allows to
characterise the service interfaces without modifying the
primitives.
–
A number of prototypes and flight software developments are
ongoing under ESA contracts and in the near future will allow
consolidate further the CCSDS standard specifications.
SOIS and SW Ref. Architecture | F. Torelli | DASIA 2011 - Malta | 17/05/2011 | TEC-SWS | Slide 28
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SOIS and Software Reference
Architecture
F. Torelli
DASIA 2011 - Malta
17/05/2011
ESA UNCLASSIFIED – For Official Use