ISO 20618:2015

INTERNATIONAL ISO
STANDARD 20618
First edition
2015-12-15


Space data and information transfer
systems — Spacecraft onboard interface
services — Device enumeration service
Systèmes de transfert des informations et données spatiales —
Services d'interface à bord du vaisseau spatial — Service
d'énumération du dispositif



Reference number
ISO 20618:2015(E)
©
ISO 2015

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ISO 20618:2015(E)

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ISO 20618:2015(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 20618 was prepared by the Consultative Committee for Space Data Systems (CCSDS) as
CCSDS 871.3-M-1, October 2014 and was adopted without modifications except those stated in Clause 2 of
this International Standard by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 13, Space data and information transfer systems.


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Recommendation for Space Data System Practices
SPACECRAFT ONBOARD
INTERFACE SERVICES—
DEVICE ENUMERATION
SERVICE
RECOMMENDED PRACTICE
CCSDS 871.3-M-1
MAGENTA BOOK
October 2014

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ISO 20618:2015(E)
CCSDS RECOMMENDED PRACTICE FOR SOIS DEVICE ENUMERATION SERVICE
AUTHORITY



Issue: Recommended Practice, Issue 0
Date: June 2006
Location: Washington, DC, USA

This document has been approved for publication by the Management Council of the
Consultative Committee for Space Data Systems (CCSDS) and represents the consensus
technical agreement of the participating CCSDS Member Agencies. The procedure for
review and authorization of CCSDS documents is detailed in Organization and Processes for
the Consultative Committee for Space Data Systems (CCSDS A02.1-Y-4), and the record of
Agency participation in the authorization of this document can be obtained from the CCSDS
Secretariat at the e-mail address below.


This document is published and maintained by:

CCSDS Secretariat
National Aeronautics and Space Administration
Washington, DC, USA
E-mail: secretariat@mailman.ccsds.org
CCSDS 871.3-M-1 Page i October 2014
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ISO 20618:2015(E)
CCSDS RECOMMENDED PRACTICE FOR SOIS DEVICE ENUMERATION SERVICE
STATEMENT OF INTENT
The Consultative Committee for Space Data Systems (CCSDS) is an organization officially
established by the management of its members. The Committee meets periodically to address
data systems problems that are common to all participants, and to formulate sound technical
solutions to these problems. Inasmuch as participation in the CCSDS is completely
voluntary, the results of Committee actions are termed Recommendations and are not in
themselves considered binding on any Agency.
CCSDS Recommendations take two forms: Recommended Standards that are prescriptive
and are the formal vehicles by which CCSDS Agencies create the standards that specify how
elements of their space mission support infrastructure shall operate and interoperate with
others; and Recommended Practices that are more descriptive in nature and are intended to
provide general guidance about how to approach a particular problem associated with space
mission support. This Recommended Practice is issued by, and represents the consensus of,
the CCSDS members. Endorsement of this Recommended Practice is entirely voluntary
and does not imply a commitment by any Agency or organization to implement its
recommendations in a prescriptive sense.
No later than five years from its date of issuance, this Recommended Practice will be
reviewed by the CCSDS to determine whether it should: (1) remain in effect without change;
(2) be changed to reflect the impact of new technologies, new requirements, or new
directions; or (3) be retired or canceled.
In those instances when a new version of a Recommended Practice is issued, existing
CCSDS-related member Practices and implementations are not negated or deemed to be non-
CCSDS compatible. It is the responsibility of each member to determine when such Practices
or implementations are to be modified. Each member is, however, strongly encouraged to
direct planning for its new Practices and implementations towards the later version of the
Recommended Practice.
CCSDS 871.3-M-1 Page ii October 2014
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ISO 20618:2015(E)
CCSDS RECOMMENDED PRACTICE FOR SOIS DEVICE ENUMERATION SERVICE
FOREWORD
Through the process of normal evolution, it is expected that expansion, deletion, or
modification of this document may occur. This Recommended Practice is therefore subject
to CCSDS document management and change control procedures, which are defined in the
Organization and Processes for the Consultative Committee for Space Data Systems
(CCSDS A02.1-Y-4). Current versions of CCSDS documents are maintained at the CCSDS
Web site:
http://www.ccsds.org/
Questions relating to the contents or status of this document should be sent to the CCSDS
Secretariat at the e-mail address indicated on page i.
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ISO 20618:2015(E)
CCSDS RECOMMENDED PRACTICE FOR SOIS DEVICE ENUMERATION SERVICE
At time of publication, the active Member and Observer Agencies of the CCSDS were:
Member Agencies
– Agenzia Spaziale Italiana (ASI)/Italy.
– Canadian Space Agency (CSA)/Canada.
– Centre National d’Etudes Spatiales (CNES)/France.
– China National Space Administration (CNSA)/People’s Republic of China.
– Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Germany.
– European Space Agency (ESA)/Europe.
– Federal Space Agency (FSA)/Russian Federation.
– Instituto Nacional de Pesquisas Espaciais (INPE)/Brazil.
– Japan Aerospace Exploration Agency (JAXA)/Japan.
– National Aeronautics and Space Administration (NASA)/USA.
– UK Space Agency/United Kingdom.
Observer Agencies
– Austrian Space Agency (ASA)/Austria.
– Belgian Federal Science Policy Office (BFSPO)/Belgium.
– Central Research Institute of Machine Building (TsNIIMash)/Russian Federation.
– China Satellite Launch and Tracking Control General, Beijing Institute of Tracking
and Telecommunications Technology (CLTC/BITTT)/China.
– Chinese Academy of Sciences (CAS)/China.
– Chinese Academy of Space Technology (CAST)/China.
– Commonwealth Scientific and Industrial Research Organization (CSIRO)/Australia.
– Danish National Space Center (DNSC)/Denmark.
– Departamento de Ciência e Tecnologia Aeroespacial (DCTA)/Brazil.
– European Organization for the Exploitation of Meteorological Satellites
(EUMETSAT)/Europe.
– European Telecommunications Satellite Organization (EUTELSAT)/Europe.
– Geo-Informatics and Space Technology Development Agency (GISTDA)/Thailand.
– Hellenic National Space Committee (HNSC)/Greece.
– Indian Space Research Organization (ISRO)/India.
– Institute of Space Research (IKI)/Russian Federation.
– KFKI Research Institute for Particle & Nuclear Physics (KFKI)/Hungary.
– Korea Aerospace Research Institute (KARI)/Korea.
– Ministry of Communications (MOC)/Israel.
– National Institute of Information and Communications Technology (NICT)/Japan.
– National Oceanic and Atmospheric Administration (NOAA)/USA.
– National Space Agency of the Republic of Kazakhstan (NSARK)/Kazakhstan.
– National Space Organization (NSPO)/Chinese Taipei.
– Naval Center for Space Technology (NCST)/USA.
– Scientific and Technological Research Council of Turkey (TUBITAK)/Turkey.
– South African National Space Agency (SANSA)/Republic of South Africa.
– Space and Upper Atmosphere Research Commission (SUPARCO)/Pakistan.
– Swedish Space Corporation (SSC)/Sweden.
– Swiss Space Office (SSO)/Switzerland.
– United States Geological Survey (USGS)/USA.
CCSDS 871.3-M-1 Page iv October 2014
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ISO 20618:2015(E)
CCSDS RECOMMENDED PRACTICE FOR SOIS DEVICE ENUMERATION SERVICE
DOCUMENT CONTROL

Document Title Date Status
CCSDS Spacecraft Onboard Interface October Original issue
871.3-M-1 Services—Device Enumeration 2014
Service, Recommended Practice,
Issue 1




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ISO 20618:2015(E)
CCSDS RECOMMENDED PRACTICE FOR SOIS DEVICE ENUMERATION SERVICE
CONTENTS
Section Page
1 INTRODUCTION . 1-1

1.1 PURPOSE AND SCOPE OF THIS DOCUMENT . 1-1
1.2 APPLICABILITY . 1-1
1.3 RATIONALE . 1-1
1.4 DOCUMENT STRUCTURE . 1-1
1.5 DEFINITIONS . 1-2
1.6 NOMENCLATURE . 1-2
1.7 REFERENCES . 1-3

2 OVERVIEW . 2-1

2.1 CONTEXT . 2-1
2.2 DEVICES . 2-3
2.3 PURPOSE AND OPERATION OF THE DEVICE
ENUMERATION SERVICE . 2-7

3 DEVICE ENUMERATION SERVICE . 3-1

3.1 PROVIDED SERVICE . 3-1
3.2 EXPECTED SERVICE FROM UNDERLYING LAYERS . 3-1
3.3 DEVICE ENUMERATION SERVICE PARAMETERS . 3-2
3.4 DEVICE ENUMERATION SERVICE PRIMITIVES . 3-4

ANNEX A DEVICE ENUMERATION SERVICE PROTOCOL
IMPLEMENTATION CONFORMANCE STATEMENT
PROFORMA (NORMATIVE) . A-1
ANNEX B SECURITY CONSIDERATIONS (INFORMATIVE) .B-1
ANNEX C ACRONYMS (INFORMATIVE) . C-1
ANNEX D INFORMATIVE REFERENCES . D-1
Figure
2-1 Device Enumeration Service Context . 2-1
2-2 Relationship between Device Enumeration Service and Other SOIS Services . 2-1
2-3 Identifiers Mapping in SOIS Services . 2-3
2-4 Device Enumeration Service and Redundancy . 2-6

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ISO 20618:2015(E)
CCSDS RECOMMENDED PRACTICE FOR SOIS DEVICE ENUMERATION SERVICE
1 INTRODUCTION
1.1 PURPOSE AND SCOPE OF THIS DOCUMENT
This document is one of a family of documents specifying the Spacecraft Onboard Interface
Services (SOIS)-compliant service to be provided in support of applications.
The purpose of this document is to define services and service interfaces provided by the
SOIS Device Enumeration Service (DES). Its scope is to specify the service only and not to
specify methods of providing the service, although use of the SOIS subnetwork services is
assumed.
This document conforms to the principles set out in the SOIS Green Book (reference [D3])
and is intended to be applied together with it.
1.2 APPLICABILITY
This document applies to any mission or equipment claiming to provide a SOIS-compatible
DES.
1.3 RATIONALE
SOIS provide service interface specifications in order to promote commonality of
functionality amongst systems implementing well-defined services. These interfaces do not
dictate implementation of interfaces or protocols supporting the services.
1.4 DOCUMENT STRUCTURE
This document comprises three sections:
– this section, containing administrative information, definitions, and references;
– section 2 containing general concepts and assumptions;
– section 3 containing the DES specification.
In addition, one normative and three informative annexes are provided:
– annex A, comprising a Protocol Implementation Conformance Proforma;
– annex B, discussing security considerations relating to the specifications of this
document;
– annex C, containing a list of acronyms;
– annex D containing a list of informative references.
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ISO 20618:2015(E)
CCSDS RECOMMENDED PRACTICE FOR SOIS DEVICE ENUMERATION SERVICE
1.5 DEFINITIONS
1.5.1 GENERAL
For the purpose of this document the following definitions apply.
1.5.2 DEFINITIONS FROM THE OPEN SYSTEMS INTERCONNECTION (OSI)
BASIC REFERENCE MODEL
This document is defined using the style established by the Open Systems Interconnection
(OSI) Basic Reference Model (reference [D2]). This model provides a common framework for
the development of standards in the field of systems interconnection.
The following terms used in this Recommended Practice are adapted from definitions given
in reference [D2]:
layer: A subdivision of the architecture, constituted by subsystems of the same rank.
service: A capability of a layer, and the layers beneath it (a service provider), which is provided
to the service-users at the boundary between the service-providers and the service-users.
1.5.3 TERMS DEFINED IN THIS RECOMMENDED PRACTICE
For the purposes of this Recommended Practice, the following definitions also apply.
application: Any component of the onboard software that makes use of the DES. This
includes flight software applications and higher-layer services.
device: A real hardware component of the spacecraft, such as a sensor or actuator, or a single
register within such a component.
notification: A service interface provided by applications that is invoked by a service
implementation to provide a means for the service implementation to deliver a message to a
set of applications.
1.6 NOMENCLATURE
1.6.1 NORMATIVE TEXT
The following conventions apply for the normative specifications in this Recommended
Practice:
a) the words ‘shall’ and ‘must’ imply a binding and verifiable specification;
b) the word ‘should’ implies an optional, but desirable, specification;
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ISO 20618:2015(E)
CCSDS RECOMMENDED PRACTICE FOR SOIS DEVICE ENUMERATION SERVICE
c) the word ‘may’ implies an optional specification;
d) the words ‘is’, ‘are’, and ‘will’ imply statements of fact.
NOTE – These conventions do not imply constraints on diction in text that is clearly
informative in nature.
1.6.2 INFORMATIVE TEXT
In the normative sections of this document, informative text is set off from the normative
specifications either in notes or under one of the following subsection headings:
– Overview;
– Background;
– Rationale;
– Discussion.
1.7 REFERENCES
The following publications contain provisions which, through reference in this text,
constitute provisions of this document. At the time of publication, the editions indicated
were valid. All publications are subject to revision, and users of this document are
encouraged to investigate the possibility of applying the most recent editions of the
publications indicated below. The CCSDS Secretariat maintains a register of currently valid
CCSDS publications.
[1] Spacecraft Onboard Interface Services—Device Access Service. Issue 1.
Recommendation for Space Data System Practices (Magenta Book), CCSDS 871.0-M-1.
Washington, D.C.: CCSDS, March 2013.
[2] Spacecraft Onboard Interface Services—Device Virtualization Service. Issue 1.
Recommendation for Space Data System Practices (Magenta Book), CCSDS 871.2-M-
1. Washington, D.C.: CCSDS, March 2014.
[3] Spacecraft Onboard Interface Services—Subnetwork Device Discovery Service.
Issue 1. Recommendation for Space Data System Practices (Magenta Book), CCSDS
854.0-M-1. Washington, D.C.: CCSDS, December 2009.
[4] Spacecraft Onboard Interface Services—Subnetwork Memory Access Service. Issue 1.
Recommendation for Space Data System Practices (Magenta Book), CCSDS 852.0-M-1.
Washington, D.C.: CCSDS, December 2009.
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ISO 20618:2015(E)
CCSDS RECOMMENDED PRACTICE FOR SOIS DEVICE ENUMERATION SERVICE
[5] Spacecraft Onboard Interface Services—Subnetwork Packet Service. Issue 1.
Recommendation for Space Data System Practices (Magenta Book), CCSDS 851.0-M-1.
Washington, D.C.: CCSDS, December 2009.
NOTE – Informative references are contained in annex D.

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Communication Management
ISO 20618:2015(E)
CCSDS RECOMMENDED PRACTICE FOR SOIS DEVICE ENUMERATION SERVICE
2 OVERVIEW
2.1 CONTEXT
The SOIS DES is defined within the context of the overall SOIS architecture (reference
[D3]) as one of the services of the Application Support Layer, as illustrated in figure 2-1.
Application
Mission
Layer
Specific
Applications
Application
Cmd & Data Time File & Message Device
Support Layer
Acquisition Access Packet Store Transfer Enumeration
Services Service Services Service Service
Transfer
Transport Protocol
Layer
Network Protocol
Subnetwork
Memory Device
Layer Packet Synchronisation Test
Access Discovery
Service
Service Service
Service Service
Datalink Convergence Protocols
Milbus SpaceWire CAN Wireless

Figure 2-1: Device Enumeration Service Context
The relationship of the DES to the other SOIS services is illustrated in figure 2-2.

Figure 2-2: Relationship between Device Enumeration Service and Other SOIS Services
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ISO 20618:2015(E)
CCSDS RECOMMENDED PRACTICE FOR SOIS DEVICE ENUMERATION SERVICE
The DES provides management and user notification of added or removed devices from a
spacecraft. Management of added devices consists of assigning a (system-wide unique)
virtual device identifier and verifying that the functions and configuration of the discovered
device match the ones required by the system. Management of removed devices consists of
revoking the (system-wide unique) virtual device identifier so that the user can no longer
access the functions provided by the device using the other Application Support Services.
The service also provides the capability to enumerate the identifiers associated with the
devices currently added and to perform queries on device metadata such as device serial
number.
The DES main goal is to assist the onboard reconfiguration functions, such as mode
management or fault detection, isolation, and recovery regarding the notification of changes
in the spacecraft configuration, and the execution of the needed operations to adjust the
onboard software to the new configuration. While the reconfiguration strategy is the
responsibility of the user applications, the DES is charged with detecting the addition or
removal of devices and the reconfiguration of the other SOIS services used to access these
devices. In addition the DES also supports the spacecraft integration and test by managing
the verification of the correct configuration of the onboard devices with respect to the
spacecraft desired configuration or by easing the insertion/removal of device simulators in
replacement of the real equipment.
The basic identification information for the devices installed in the system is retrieved by the
subnetwork Device Discovery Service (DDS), reference [3], and used by the DES to assign a
system-wide unique identifier to each device so that each can be accessed by the user
applications using the appropriate functional interface (using the Device Virtualisation
Service [DVS], reference [2]), device access protocol (using the Device Access Service
[DAS], reference [1]), and subnetwork services (namely Memory Access Service [MAS],
reference [4], or Packet Service [PS], reference [5]).
The mapping between the identifiers used by the services and protocols is also illustrated in
figure 2-3.
Command & Data Acquisition Service and protocol parameters as well as device-specific
access algorithms are preinstalled in the onboard software. The use of DES does not imply
any dynamic code generation or compilation at run-time; instead, it allows selection of
predefined service instances already available in the onboard software system.
The interactions within the other SOIS services for what concerns the device IDs and
subnetwork addresses assignments are done via the Communication Management entity;
therefore these operations are not covered by the service interface specified in this document.
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ISO 20618:2015(E)
CCSDS RECOMMENDED PRACTICE FOR SOIS DEVICE ENUMERATION SERVICE
User Application
Device Virtualisation Virtual Device Identifier
Service (system-wide unique)
Device Access Service Physical Device Identifier
Packet or Memory Spacecraft Network Address
Access Service (system-wide unique)
Subnetwork-Specific
Subnework-Specific Address
Protocol
Hardware Device

Figure 2-3: Identifiers Mapping in SOIS Services
2.2 DEVICES
2.2.1 ADDING DEVICES
Two mechanisms are available for adding a device by means of the DES:
a) ‘Bottom-up’. Discovery of added devices is provided by DDSes within the different
subnetworks and notified to the DES (mandatory feature).
b) ‘Top-down’. Service users (higher-level services or applications) notify the DES of
an added device (optional feature).
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In either case, the following information is provided to the DES:
a) Device Serial Number, the unique identifier of the physical device to distinguish
between devices of the same type (e.g., gyro mounted on axis X, gyro mounted on
axis Y, etc.);
b) Device Type, the identifier of the functional interface supported by the device when
accessed using the DVS;
c) Spacecraft Network Address, the identifier of the device in the spacecraft network,
identifying the subnetwork and the device within the subnetwork.
The DES joins information from two sources. One is the DDS (real configuration), which
provides as minimum the Spacecraft Network Address and Device Serial Number. The other
is the spacecraft configuration data provided by the spacecraft designers as a configuration
table (stored inside the DES or made available through an onboard file system) and providing
for each device the association between Device Serial Number, Spacecraft Network Address,
and Device Type, and device location/orientation.
Matching these two sets of information, the DES then reconfigures DVS and DAS (by using
DVS and DAS management interfaces to modify their Management Information Bases
[MIBs]) to enable user access to the service provided by the device. Management consists of:
a) verification that a device with the attributes mentioned above is foreseen by the
spacecraft configuration (if the check is negative an error is reported); otherwise
b) assignment of the Virtual Device Identifier (system-wide unique) to be used in the
DVS primitives;
NOTE – To ease system integration and space operations, it is advised to use a
deterministic algorithm to assign the device identifiers so that a given device
always receives the same identifier every time it is added/discovered.
c) association of the Virtual Device Identifier assigned at b) with the Physical Device
Identifier used by DAS to the added device in the DVS MIB (reference [2]);
d) association of the Physical Device Identifier (system-wide unique) with the
Spacecraft Network Address in the DAS MIB (reference [1]) to, in order to access the
device in its subnetwork.
Finally, the DES notifies any associated application of the added device by means of a
notification. A notification is a service interface provided by applications that is invoked by a
service implementation to provide a means for the service implementation to deliver a
message to a set of applications. The parameters of this DES notification include the device
attributes defined at a), b), c) and d).
NOTE – The mechanism to associate an application with DES notification is
implementation-dependent.
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2.2.2 REMOVING DEVICES
Two mechanisms are available for removing devices by mean of the DES:
a) ‘Bottom-up’. Discovery of removed devices is provided by the DDS within the
different subnetworks and notified to the DES (mandatory feature).
In this case, the following information is provided to the DES:
Spacecraft Network Address associated to the removed device.
The remaining associated device identifiers can be derived from the Spacecraft
Network Address using the MIBs of the DAS and DVS where the associations
between identifiers are maintained.
b) ‘Top-down’. Service users (higher-level services or applications) notify the DES of a
removed device (optional feature).
In this case, the following information is provided to the DES:
Virtual Device Identifier, the system-wide unique identifier for the removed device.
The DES then reconfigures the DAS and DVS to remove user access to the service provided
by the device. Management consists of:
a) invalidation of the Spacecraft Network Address in the DAS MIB;
b) invalidation of the Physical Device Identifier in the DVS MIB;
c) revocation of the Virtual Device Identifier.
Finally, the DES notifies any associated applications of the removed device by means of a
notification. The parameters of this DES notification include the Virtual Device Identifier of
the removed device.
NOTE – The mechanism to associate an application with the DES notification is
implementation-dependent.
2.2.3 MIB CONSIDERATIONS
The DES MIB contains the following information:
– Virtual Device and Value Identifier Resolution Table, being a set of managed
parameters that map logical device and value identifiers onto individual underlying
services and their associated available addressing mechanisms.
– Physical Device and Value Identifier Resolution Table, being a set of managed
parameters that map physical device and value identifiers onto individual underlying
services and their associated available addressing mechanisms.
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