ISO 18427-2013 PDF

Full title and description

Space data and information transfer systems — Spacecraft Onboard Interface Services — Subnetwork Synchronization Service. ISO 18427:2013 defines the SOIS Subnetwork Synchronisation Service: the service interfaces and behaviour required to distribute time and synchronization events across an onboard subnetwork (service specification only, not link-level protocols).

Abstract

ISO 18427:2013 is part of the Spacecraft Onboard Interface Services (SOIS) family and specifies the Subnetwork Synchronisation Service used on spacecraft onboard subnetworks. The document defines the service primitives, parameters and management objects required to provide time distribution and event/heartbeat synchronization to distributed onboard applications; implementation over specific data links is out of scope.

General information

• Status: Published.
• Publication date: 2013 (published May/June 2013).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 49.140 (Space systems and operations).
• Edition / version: Edition 1 (2013).
• Number of pages: 23.

Scope

Specifies the SOIS Subnetwork Synchronisation Service: the required service primitives, parameters, message semantics and management objects for distributing time and synchronization events to nodes on an onboard subnetwork. The standard defines the service behaviour and conformance proforma but does not mandate link-level protocol implementations; link-specific protocols are to be documented separately (typically in CCSDS or mission/agency profiles). ISO 18427:2013 is intended to be used together with the SOIS Green Book and related SOIS documents.

Key topics and requirements

• Service definition: required primitives (requests/responses/indications) for time distribution and synchronization events.
• Time distribution semantics: absolute time messages, relative/timebase updates and timestamping conventions.
• Event and heartbeat services: one-shot and periodic event delivery for coordinated activities and health monitoring.
• Multicast/broadcast support: assumptions and suggested use where underlying links support group delivery for efficient synchronization.
• Management Information Base (MIB) and conformance statement: objects and a proforma for declaring compliance with the service.
• Quality-of-service and security considerations: conceptual guidance; concrete mechanisms depend on link-level implementations.
• Link/protocol independence: the standard specifies the service only; protocols that realize the service on specific data links are documented separately (CCSDS or mission profiles).

Typical use and users

Used by spacecraft system architects, avionics and payload engineers, onboard middleware and software developers, mission integrators, and verification/test teams to provide a common timebase and synchronized event delivery across distributed onboard subsystems. It supports coordinated payload operations, deterministic control loops, consistent timestamping of telemetry and science data, and cross-mission interoperability where SOIS is applied.

Related standards

ISO 18427:2013 is part of a broader SOIS suite and is typically used alongside other ISO/CCSDS SOIS documents such as ISO 18424 (XTCE), ISO 18425 (Subnetwork Packet Service), ISO 18426 (Subnetwork Memory Access Service), ISO 18428 (Subnetwork Device Discovery Service), ISO 18438 (Subnetwork Test Service) and other SOIS/CCSDS publications and the SOIS Green Book.

Keywords

SOIS, Subnetwork Synchronization, time distribution, synchronization service, spacecraft onboard interfaces, CCSDS, timebase, event/heartbeat, service primitives, conformance.

FAQ

Q: What is this standard?

A: ISO 18427:2013 specifies the Spacecraft Onboard Interface Services (SOIS) Subnetwork Synchronisation Service — the service-level API and behaviour for distributing time and synchronization events across an onboard subnetwork.

Q: What does it cover?

A: It covers the service primitives, parameters, message semantics, management objects (MIB) and a conformance proforma for the synchronization service; it does not define how the service is implemented on particular data links (those are documented in CCSDS or link/protocol profiles).

Q: Who typically uses it?

A: Spacecraft system architects, avionics and payload engineers, onboard software/middleware developers, mission integrators, standards and verification teams — anyone implementing or validating SOIS-compliant synchronization for spacecraft onboard networks.

Q: Is it current or superseded?

A: ISO 18427 was published in 2013 (Edition 1) and, as of its last ISO review cycle, remains a published SOIS part. Users should check ISO/TC 20/SC 13 or national standards bodies for any later revisions or withdrawals before procurement or certification.

Q: Is it part of a series?

A: Yes — it is one document in the SOIS family of standards (ISO and CCSDS publications) that together define onboard services (time/access/memory/packet/device discovery/test, etc.). Many ISO SOIS parts are direct adoptions or adaptations of CCSDS SOIS (Magenta Book) publications.

Q: What are the key keywords?

A: Synchronization, time distribution, SOIS, subnetwork, service primitives, timestamping, multicast, heartbeat, conformance, CCSDS.