Example of EDS usage in SOIS [recap from SAFI meeting 23/6/2012]

ESA UNCLASSIFIED – For Official Use

Example of EDS usage in SOIS[recap from SAFI meeting 23/6/2012]

F. TorelliCCSDS SOIS WG, Darmstadt17/04/2012

Example of SOIS EDS | F. Torelli | ESTEC | 23/06/2011 | Slide 2


Introduction

1. Objective:

– To give an example of how SOIS C&DA services and EDS can map to Star Tracker TM/TC ICD.

2. Inputs:

– STR_TM_TC_packets_V4.xls

– Report from CCSDS SOIS Spring Meeting 2011

– Notes from CCSDS SOIS Fall Meeting 2010

3. Entities involved:

– Dictionary of Terms (DoT)

– Electronic Data Sheet (EDS)

– Device Access Service (DAS)

– Device Virtualisation Service (DVS)



SOIS PnP Architecture

Device EnumerationService


Device VirtualisationService


Device AccessService


SubnetworkPacket or Memory

Access Service


Access Service

SubnetworkProtocol

Implementations

SubnetworkProtocol

Implementations

SubnetworkDevice Discovery

Service


Service

SubnetworkPlug-and-Play

Protocol


Protocol

SubnetworkManagement and

Configuration


ConfigurationPolicyPolicy

SOIS

SubnetworkImplementation

Hardware

Applications

DoTDoT

Standardised interface including semantics.Ref. sheet 1 in STR_TM_TC_packets_V4.

Device specific functional interface.Ref. sheet 2, 3, 4 in STR_TM_TC_packets_V4.

Contains syntactic and semantic types.

Contains the ICD of the devices w.r.t. the SOIS service interfaces.

EDSEDS



Dictionary of Terms & Electronic Data Sheet

– The DoT contains the attributes to be used to describe the device and in particular its interfaces (i.e. syntactic and semantic types).

– The DoT is the vocabulary used to build the EDS for a particular device.

– The elements of the DoT arranged (and instantiated) in the EDS for a specific device allow to associate a meaning to the raw data in the “TM and TC” of that device.

– The EDS describes the mapping between the layers in the SOIS Command & Data Acquisition (C&DA) in terms of service primitives and their parameters.

– The EDS describes the mechanisms to send/receive data to/from the devices and how to elaborate them along the C&DA stack.



Example of DoT (1/2)

Basic Syntactic Types:

Type Identified Max Range Comment

Real (single precision) Type [-inf, inf] Ranges of specific attributes can be smaller

Real (double precision) Type [-inf, inf] Ranges of specific attributes can be smaller

Integer (32bits) Type [-231, 231-1] Ranges of specific attributes can be smaller

Natural (32bits) Type [0, 232-1] Ranges of specific attributes can be smaller

Natural (16bits) Type [0, 216-1] Ranges of specific attributes can be smaller

Time (64bits) Type [(0, 0), (232-1, 1-2-24)] CUC format (s, sub-s)

Composite Syntactic Types:

Type Identifier Structure Range Comment

Quaternion Type Array of 4 Real(double) [-1, 1]

Real Vector Type Array of 3 Real(double) [-inf, inf] Ranges of specific attributes can be smaller

Integer Vector Type Array of 3 Integer(32bits) [-231, 231-1] Ranges of specific attributes can be smaller

The provided types are examples used along the presentation for practical reasons, but are not the finalised elements of the SOIS DoT.



Example of DoT (2/2)

Semantic Types:

Type Identifier Syntactic Type Unit Comment

Final Attitude Quaternion Type - Reference frame: J2000 frame --> sensor frame

Final Attitude Measurement Time

Time Type s, ms Time elapsed between the last synchronisation signal and measurement

Final Angular Rate Real Vector Type rad/s w = vector(3) Reference frame: sensor frame vs inertial frame

Final Angular Rate Measurement Time

Time Type s, ms Time elapsed between the last synchronisation signal and measurement

Mode Natural or Enum Type - Sensor mode

Direct Command Natural or Enum Type - Command Id (e.g. reset, Standby)

Linear Velocity Real Vector Type m/s S/C velocity vector = vector (3) in J2000 frame

Raw Attitude Quaternion Type - Reference frame: J2000 frame --> sensor frame

Raw Linear Velocity Int Vector Type m/s Velocity / Rc

SubNetwork Address Natural Type - Global address of the unit among the subnetwork

Service Type Natural or Enum Type - SOIS Service Id (e.g. PS, DAS)

The provided types are examples used along the presentation for practical reasons, but are not the finalised elements of the SOIS DoT.



Example of EDS for DAS

Subset of EDS for SODERN HYDRA (DAS Subnetwork)

EDS content for User (DAS) EDS content for Target (Subnetwork)

DoT Item Value DoT Item Value

–Device Id –STR-A – Subnet Addr

– Service Type

– Service Class

– STR address discovered by the subnetwork services

– Packet Service

– Best Effort

…

–Service Primitive

–Value Id

–Acquire_From_Device

–QRsFil


–Channel

–Pkt Type

–Pkt Field Position

–Pkt Field Size

–Packet_Receive

–SAInfo

–Attitude Tracking Mode Telemetry

–Byte pos. 16

–32bytes…


–Value Id

–Command_Device

–VabYc


–Channel

–Pkt Type

–Pkt Field Position

–Pkt Field Size

–Packet_Send

–IdUpdate

–Linear Velocity Update Command

–Byte pos. 8

–32bytes

Global subnetwork address is function of the subnetwork type (i.e. Mil1553), STR address within the subnetwork (i.e. RT 03), but also of the subnetwork management policy.



Example of DAS implementation using EDS information

To acquire the value Quat of QRsFil (filtered fused attitude quaternion), the Device Access Service user shall invoke the following service primitives:

Acquire_From_Device.request(DASAP, TransId, STR-A, QRsFil);

…

Acquire_From_Device.indication(DASAP, TransId, Quat, ErrorCode);

DAS service primitives can then be implemented by means of Packet Service primitives calls, for example as follows:

Acquire_From_Device.indication(DASAP, TransId, Val, ResultMeta)

{

Packet_Receive.indication(PSSAP, Mil-RT03, BE, SAInfo, PktData);

for (I = 0;I < Pkt Field Size; I++)

Val[I] = PktData[I + Byte Pos];}

In red, relevant output parametersIn blue, elements of the EDS



Example of EDS for DVS

Subset of EDS for SODERN HYDRA (DVS DAS)

EDS content for User (DVS) EDS content for Target (DAS)

DoT Item Value DoT Item Value

–Device Id –STR-Nom – Device Id – STR-A

…


–Attribute Id

–Conversion Law

–DVS_Acquire

–Final Attitude

–Identity


–Value Id

–Acquire_From_Device

–QRsFil

…


–Attribute Id

–Conversion Law

–DVS_Command

–Linear Velocity

–Double-To-Int


–Value Id

–Command_Device

–VabXc


–Value Id

–Command_Device

–VabYc


–Value Id

–Command_Device

–VabZc



Example of DVS implementation using EDS

To command the update of the linear velocity (VabXc, VabYc, VabZc) to value Vel, the Device Virtualisation Service user shall invoke the following service primitives:

Command_Device(STR-Nom, Linear Velocity, Vel, ErrorCode);

DVS service primitives can then be implemented by means of DAS primitives calls, for example as follows:

Command_Device(Device Id, Attribute Id, Value, ResultMeta){

if (Device Id == STR-Nom)Dev = STR-A;

elseDev = STR-B;

if (Attribute Id == Linear Velocity){

VelX = Double-To-Int(Value[0]);VelY = Double-To-Int (Value[1]);VelZ = Double-To-Int (Value[2]);Command_Device.request(DASAP, TransId0, Dev , VabXc, VelX);Command_Device.request(DASAP, TransId1, Dev , VabYc, VelY);Command_Device.request(DASAP, TransId2, Dev , VabZc, VelZ);

}}

In green, relevant input parametersIn blue, elements of the EDS

More elaborated conversion law can be applied here



SOIS PnP Architecture - Recap








Access Service


Access Service

SubnetworkProtocol

Implementations

SubnetworkProtocol

Implementations


Service


Service


Protocol


Protocol


Configuration


ConfigurationPolicyPolicy

SOIS

SubnetworkImplementation

Hardware

Applications

DoTDoT

Device specific functional interface, uses the existing equipment capabilities and fits in the SAVOIR-FAIRE SW architecture.

Types to be defined with the main contribution of SAVOIR-SAFI WG.

EDS contains different sections covering the different SOIS service/abstraction layers.Its content is mainly filled in by equipment manufacturer.

EDSEDS

Framework, specifications of formats and mechanisms need to be defined by SOIS WG to enable definition and usage of DoT, EDS and C&DA services.



Summary

– Examples of DoT and EDS using elements of the provided Star Tracker TM/TC ICD have been presented as well as a possible service implementation.

– EDS, DVS and DAS allow flexibility in the usage and implementation, still preserving standard service interfaces.

– DAS interface (device specific functional interface) and the related sections of the EDS can be defined and used with the existing equipment without modifications.

– The mechanisms to access DoT and EDS and their formats are under definition by the SOIS WG.

– The implementation of DAS and DVS can easily follow a recurrent design pattern, which would in the future also enable auto-coding of part of the services and user applications.

– SAVOIR-SAFI in the short term would be very helpful in contributing to the definition of the Common Data Dictionary content (semantic and syntactic types) in order to represent the interfaces of the existing equipments.

Example of EDS usage in SOIS [recap from SAFI meeting 23/6/2012]

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