To ensure interoperability and conformity of automation equipment from different field device manufacturers, certification by an accredited test laboratory is mandatory for PROFINET devices. During the certification process, devices are tested to determine if they comply with the applicable IEC standards and to ensure they function seamlessly within an automation system. While every PROFINET device must be certified, the effort required to achieve certification varies depending on the technology used. Unfortunately, many device manufacturers only begin to address this immediately before a product is released, an approach which increases the risk of it being non-compliant. Therefore, pre-certification is recommended because it can significantly reduce the potential for problems during certification testing. This article provides an overview of the PROFINET certification process. Furthermore, it shows how partnering with a company specialising in precertification increases the likelihood of a PROFINET device being first-time certified, saving time and cost.
Profinet enables consistent communication from process management to the field level. Some of the benefits of using it as an industrial network include the following:
- scalable real-time communication to isochronous motion control
- safety to protecting humans, equipment, and the environment (safety)
- security feature to protect equipment against unauthorised access
- provides detailed and actionable diagnostics
- enables flexible network topologies (like star and line) when using an integrated multi-port switch to connect automation equipment
- supports a variety of transmission media, e.g., copper, fibre optic cable, wireless, etc.
PROFINET is designed to be future-proof by supporting Time Sensitive Networking (TSN) and integrating Open Platform Communication Unified Architecture (OPC UA) to manage communication between controllers and the back-end systems monitoring the manufacturing process.
Profinet International (PI) is the umbrella group responsible for Profinet certification. PI does not allow product self-certification, so devices must be tested in an approved Profinet International Testing Laboratory (PITL) for conformance before they are launched. A product which passes the testing process is issued a certificate by PI. Products are certified according to IEC 61158 and IEC 61784 and are tested to demonstrate the correct implementation of the following:
- Hardware interface
- PROFINET mandatory and optional functionality
- Reaction to faulty behaviour
- Robustness against netload
- Proper operation in a reference automation environment
- State machines
- GSD file
PROFINET GSD files describe a device’s functionality and are written in XML format (hence they are sometimes called “GSDML files”). A GSD file contains configuration information, parameters, modules, diagnostics and alarms, and vendor and device identification. Manufacturers must provide a GSD file for every device being certified. The duration and cost of testing depend on the supported features, device complexity, variants, and other factors.
Pre-Certification Reduces the Risk of Non-Conformance
Implementing and certifying a Profinet device can be daunting for industrial device manufacturers using the protocol for the first time. PI provide two separate documents covering the implementation of Profinet in field devices and the certification path, containing more than 40 pages of information each. This represents a steep learning curve which increases the risk of a device not achieving certification on first testing, meaning manufacturers must reapply – further delaying a project while also incurring the costs of a retest. The advantage of collaborating with an external technology or development partner when developing a PROFINET interface is that it allows the device manufacturer to concentrate on its core areas of expertise, reducing development risks and time to market. In addition, an external specialist’s experience helps ensure that the design of the automation device is competitive and its communication interface is Profinet compliant before it is presented for testing at a PITL.
Partner with Profinet Experts
RT-Labs has more than 20 years of experience specialising in industrial communication protocol, including assisting manufacturers in implementing and pre-certifying Profinet field devices. We provide a low-footprint Profinet protocol software stack and guide manufacturers through its implementation and pre-certification to maximise the likelihood of devices achieving first-time certification. RT-Labs’ software-based implementation significantly reduces device development costs. RT-Labs partners with industrial device manufacturers to help them build up PROFINET expertise in a manageable and time-efficient way, allowing them to focus on other aspects of project development.