SHOWCASE 2014AEROSPACETESTINGINTERNATIONAL.COM

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Typical IMA-based aircraft architectures consist of computing devices, the aircraft

data communication network (ADCN) and distributed signal interface devices. The definition of IMA resources is the reusability of standardized hardware equipment, network technology (ARINC 664) and software applications. These can be combined into systems with different specifications and for various aircraft. To realize this flexibility, the IMA resource can be adapted to the required needs with specific configuration data.

In an IMA-based aircraft, the ADCN is one of the most complex parts that integrates various systems and transports data of different criticality and rate. As the entire functionality of an IMA-based architecture depends on the correct behavior of the ADCN, it is important to have confidence in the ADCN functionality at an early stage of the aircraft development process. For that reason, integration and verification of the ADCN are done on multiple levels.

At the equipment functional level, the network components are verified to function properly within their usage domain. The next level is the equipment configuration verification. At this level, the required functions of a network component are verified with reference to a specific configuration.

The next levels of verification are done with focus on the complete network. The ADCN configuration is subject to a static verification through mathematical analysis on a network model. A dynamic verification of a network should be done at the end of integration testing at ADCN level to validate the static verification results. At this level, the entire network – all ARINC 664 switches in the real aircraft system configuration – is available as real equipment. The end system behavior is simulated and the network performance (for example, timing, data loss) as well as required network capability (for example, data loading, simple network management protocol (SNMP) support) is verified.

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Integrated Modular Avionics (IMA) will be the backbone of a centralized aircraft data communication networkBY DIETER KONNERTH AND BERND MATTNER

INTEGRATING THE NET

At aircraft integration level, the ADCN is integrated with all other systems. This integration and verification level normally consists of lab, ground and flight tests.

TEST SYSTEM APPROACHIntegration problems of an ADCN are discovered with all other system equipment connected and operating. As the ADCN integration normally is realized at aircraft level, this is very late in the aircraft development process. It is common sense that errors detected at this stage are very expensive.

It is for this reason that TechSAT, a company with a great deal of experience in AFDX (ARINC 664) technology and integration facilities for the aerospace sector, together with its partners, decided to revolutionize its approach to AFDX integration and verification. As a result, an ADCN test

system was designed that is being used by a major supplier of avionics products and services in China’s aerospace industry.

Some major requirements for such a test system are derived from the static verification that shall be validated. Hence the test system has to provide capability to test that a timing schedule of a network configuration is valid as well as that the network real-time behavior is deterministic.

To legitimate the effort for another integration and verification test system at ADCN level, it has to provide added value. For that reason, the test system has to support the verification of functionality that is not covered by static verification. With the ADCN test system, different operational states,

DIETER KONNERTH

BERND MATTNER

ADS2 RT-host with AFDX TAP

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INTEGRATING THE NET

BELOW: ADCN test architecture for the AFDX network

such as normal operation, power up or reset can be tested. Further aspects that can be investigated are health monitoring and time synchronization.

One of the major benefits of a test system at the ADCN level is the ability to verify the robustness of the network. With simulated end systems, it is easy to inject nearly all kinds of errors and to check the network behavior in case of data errors or failure modes where one or more switches fail.

The test system architecture should be scalable to the size of the ADCN (for example, number of switches or end systems).

TEST ARCHITECTUREAll the requirements are achieved in a very modular design that in the end

led to the need to develop a dedicated TechSAT AFDX Test Access Port (TAP) with two feed-through Ethernet interfaces and to revise the TechSAT TimeMaster system.

One AFDX TAP is designated to each network hardware connection to monitor the ARINC 664 traffic in the ADCN. All AFDX TAPs are hardware time-synchronized for data time-stamping. ARINC 664 boards with dedicated end system simulations that can be loaded with a configuration corresponding to the referring end system interface control document (ICD) are provided to autonomously

perform end system network traffic.The test architecture is configured

in such a way that it can be used for ADCN integration with test systems from subsystem level over the ADCN level to the aircraft integration level in a laboratory. To increase the usability of the test system, an ADCN Test Suite – an automated test procedure – is provided that supports verification of all aspects of the ADCN. Most of the Test Suite is generated from the aircraft ICD. z

Dieter Konnerth is director of research and development and Bernd Mattner is project manager at TechSAT GmbH, based in Germany

AIRCRAFT COMMUNICATION

The IMA-based aircraft architecture is one of the major solutions to meet the demands of short time-to-market and the requirement for cost-effective aircraft development and operation. New large commercial aircraft, such as the Boeing 787, Airbus A350 and COMAC C919, have already been realized with IMA-based

architecture. Some of the regional jet manufacturers are now interested in the IMA-based approach. More and more aircraft system suppliers feel impelled to provide their products as an IMA resource. For that reason, it is important to find effective solutions in order to integrate and certify IMA-based architectures.

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