ISO 20242-5:2020

Overview

ISO 20242-5:2020 - Application Program Service Interface (APSI) - is part of the ISO 20242 series for industrial automation systems and integration. The standard defines the formatting, syntax and semantic rules for describing an object‑oriented interface that application programs use to access services provided by a coordinator and to configure virtual devices and their runtime environment. ISO 20242-5 is technology‑neutral and focuses on service semantics rather than a specific programming-language binding.

Key topics and technical requirements

• APSI model: An object‑oriented service model describing classes, attributes and methods for coordinator services; services are synchronous by default with optional asynchronous operation via callbacks.
• Coordinator services: Defines how an application accesses device drivers through a coordinator that manages synchronization, events and memory separation between application data and device data.
• Parameterization & PID: Support for dynamic linking/unlinking of applications and device drivers and for instantiation of virtual devices using a Parameterization Instance Description (PID) based on Device Capability Descriptions (DCD).
• Workspace concept: Grouping of coordinators and resources to provide access points for applications; includes workspace structure, extension and transfer mechanisms.
• Interface variants: Multiple access levels are defined - notably the mandatory Smart Access Interface (SAI) (device‑neutral) and optional Full Access Interface (FAI) (allows device‑specific access); Extended Access Interface (EAI) is also defined.
• Data handling: Rules for data types, data monitoring, streaming, callback registration, and memory isolation to keep device-specific elements encapsulated.
• Error handling & conformance: Error management patterns are standardized and conformance test methods/criteria are specified in annexes.
• Documentation mappings: The standard defines services, not language bindings - implementations must document mappings (e.g., CORBA, Java, C++) and platform specifics.

Applications and practical value

ISO 20242-5 is intended for environments requiring robust, device‑independent access to measurement, automation and testing resources. Typical applications:

• Test automation and measurement systems in automotive and industrial manufacturing
• Device driver vendors creating ISO‑compliant virtual device interfaces
• Tool developers building parameterization and integration tools (PID editors, coordinators)
• System integrators and OEMs seeking OS‑ and network‑independent device integration and driver certification

Benefits include device and OS independence, clearer separation between application and device semantics, and a standardized basis for driver certification and interoperable test tools.

Related standards

• ISO 20242-1 through ISO 20242-4 (Overview, Resource Management, Virtual Device Service Interface, Device Capability Profile Template)
• ISO 13209-1 and ISO 13209-2 (OTX - Open Test sequence eXchange format)

Keywords: ISO 20242-5, APSI, Application Program Service Interface, industrial automation, virtual device, coordinator, PID, device drivers, SAI, FAI, device independence.