With the advent of Industry 4.0 and its rapid adoption across the industrial automation and manufacturing domains, majorly due to the deployment of the Industrial Internet of Things (IIOT), Open Platform Communication United Architecture (OPC-UA), has witnessed significant implementations, driving operational effectiveness and faster business decisions.
An important instrument of Industry 4.0, the OPC-UA standard is one of the leading connectivity protocols designed for secure and reliable industrial automation that has helped in promoting factory modernization in manufacturing and industrial equipment and processes. Another important factor accelerating the growth of OPC-UA is the advent of 5G which has resulted in an emergence of M2M communication opportunities.
OPC-UA is a standard data exchange protocol (IEC 62541) that allows industrial equipment and applications (e.g., PLC, HMI, Sensors, client, etc.) to communicate securely and reliably. It follows the Standard Client/Server and Publisher/Subscriber communication paradigms that are appropriate for transferring manufacturing data and calling services between various components and applications as defined in the OPC-UA architecture.
Historically, the legacy systems and equipment followed the classic OPC standards (HDA, DA, alerts/events), which were platform-dependent i.e., Windows-based. However, OPC-UA, with its open architecture and approach, is platform-independent as it is now supported on Windows, Linux, Mac, Android, etc. Now, with the co-existence of legacy systems supporting older classic OPC standards and the new OPC-UA standard, quality assurance approaches need to be revised to meet the quality goals of the entire industrial automation/manufacturing cycle encompassing both standards.
With the wide adoption of OPC-UA, a number of implications arise that need to be considered as valid focus areas for an impactful QA assurance strategy:
Integration: With a standard security model, OPC-UA allows for easy integration into pre-existing IT networks. OPC-UA works via OSI Layer TCP port, allowing for simple server (residing in an embedded device) and client (residing in a Gateway/Cloud platform) connectivity.
Compatibility: Being a new protocol, OPC-UA is not compatible with legacy implementations i.e. OPC-DA. Therefore, a UA wrapper function is required to connect. This configuration/scenario needs to be validated additionally.
Cross-platform support: OPC-UA can be easily integrated with Windows, Linux, Android, etc and these servers can be hosted on the embedded systems i.e., on PLC, etc. needing additional validation.
Applications: One of the interesting design aspect of OPC-UA is that it can be used for supervisory control. This allows for field and control level systems to directly send data to management level platforms via a common API, supporting multi-vendor controllers.
OPC-UA test/validation strategy proposes is a hybrid model incorporating testing on real-field devices. It is in conjunction with an open-source software or in-house OPC-UA server simulators designed as per the standards available since OPC-UA is a client and server model which may have several clients and servers in a complex system.
Different types of test levels like functional, integration, system and non-functional, negative compliance, and acceptance need to be part of a test strategy. Also, to reduce test cycle time, test automation must be part of the overall strategy.
Functional Testing: Feature-wise test case development and functional test execution can be performed on the identified features that are implemented. Some of the major features OPC UA support are Security Models, Authentication, Auditing, Services, Data Access, Alarms and Conditions, Aggregates, PubSub, Historical Access, Mapping, and Redundancy.
Integration Testing: Between the OPC-UA Server and its communication with Level 4 (Cloud) and Level 0 Field Device, communication should be the focus of an integration test plan (MODBUS TCP, OPC-UA, Read/write from the cloud via MQTT).
System Testing: It focuses on verifying the end-to-end system validation using real sensors and PLC, embedded servers, clients, cloud platforms, etc. Some key tests would be device onboarding to the cloud, access to the cloud via the test application, device discovery over the IP network for various protocols, subscription of the properties from the endpoints from the cloud, validation of Change of Value (COV) from the end device to the cloud, Modbus polling and data transfer to the cloud on COV, data storage on connectivity loss and data prorogation on connectivity restoration
Performance Testing: This can be carried out to determine the software performance concerning aspects such as actual KPIs against which these areas are to be tested will be defined as capacity handling, reliability, max load, response time, and Performance testing of the OPC-UA server will be done using the simulators in level 0.
OPC-UA has been redefined and differentiated in most aspects from OPC Classic and is now platform agnostic and can support multiple operation systems with enhanced security. OPC-UA has become an acceptable standard for industrial automation and the manufacturing industry. The ability to accommodate legacy systems caters to plants and factories that do not necessarily have the budget to purchase new equipment and IT infrastructure, which is another major positive in manufacturing.
Therefore, quality assurance is a critical success factor in OPC-UA architecture and IIoT-driven industrial automation systems. A well-thought-out, holistic testing approach with embedded Level 0 device and software components (closely integrated and grounded in automated testing and based on industry best practices) developed through innovative and proven expertise provides the much-needed predictability and assurance to the OPC-UA standards.
About the Author
Jason Chandralal is General Manager with Happiest Minds and heads the Industrial & Embedded Testing practice with more than 20 years of experience. Happiest Minds Technologies Limited, a Mindful IT Company, enables digital transformation for enterprises and technology providers by delivering seamless customer experiences, business efficiency and actionable insights. We do this by leveraging a spectrum of disruptive technologies such as: artificial intelligence, blockchain, cloud, digital process automation, internet of things, robotics/drones, security, virtual/augmented reality, etc
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