Rapid technological developments in recent times have led to a huge increase in the importance of software-equipped measuring instruments and systems. ‘’In the past, 80% of the characteristics of instruments were determined by the hardware – now 80% of the characteristics of instruments are determined by the software. We are seeing a big increase in the significance of software-related knowledge development. This is because many instruments are rejected on application precisely because of the software used,’’ says Jan Konijnenburg.
The WELMEC Guide 7.2 forms the basis for the software requirements governing the design, verification and legislation for a range of measuring instruments and systems. During the past 10 years, Jan Konijnenburg has been working with NMi, where he is in charge of type approvals in various segments. He is also one of the members of the WELMEC 7 group. Due to his active involvement in this international working group he now finds himself in an intermediary position between manufacturers and the regulator. Jan also works in the industry as an approval engineer in the weighing of instruments. Much of his work is on the software side and during that period he has developed extensive practical experience in this area.
Because of his expertise and experience, Jan is the designated person within NMi to run the training courses in relation to the Measuring Instruments Directive (MID). The ‘MID software requirements’ course is run a number of times each year, both online and on location. The training is designed for developers of measuring instruments. The course is also suitable for end users and notified bodies. In this interview he explains the importance of the training and tells about his experiences with WELMEC 7.2.
Why is Welmec 7.2 used in Europe?
‘’A lot of measuring instruments used for commercial purposes are regulated under the MID. This is the European Measuring Instruments Directive which sets out the essential requirements in respect of these instruments. To meet the MID requirements, one must refer to the harmonised standards (EN/IEC standards) of the normative documents drawn up by the OIML (International Organization of Legal Metrology). WELMEC also prepares guides to explain these standards and provides guidelines for Notified Bodies. Welmec consists of a number of working groups who are involved in drafting and writing up these guides. The WELMEC Working Groups comprise of representatives from the European member states and from the industry.
The MID sets out very stringent requirements in relation to the software: both the software and the measurement data have to be sufficiently secure. But what does ‘secure’ mean? The technical requirements governing the hardware and functionality of for example a weighing machine, a kWh meter or a liquid measurement instrument are based on the OIML Recommendations or the IEC and EN standards. The requirements which must be met by instruments are clearly set out in these regulations. There are no standards governing software as yet. For this reason WELMEC decided to prepare a guide that will provide a framework for the requirements applicable to software: the WELMEC-guide 7.2
‘’NMi has started giving training courses in the area of software, because we have learned that many instruments are rejected on application because of the software used. This happens because many manufacturers are unclear about the requirements in the WELMEC 7.2 guide. If manufacturers and developers follow the WELMEC 7.2 guide, they are in keeping with the regulations and their measuring instruments and systems will be approved within Europe. In organising these training courses, NMi hopes to be of assistance to manufacturers in being better prepared for the software tests by the Notified Bodies, and so gain speedier access to the market.’’
What is your experience as a trainer with WELMEC 7.2?
‘’In the market there is a great demand for more information regarding the software requirements. Such information has been very limited to date. This is why it has become so inaccessible for many people. In this training course I will be able to point out the bottlenecks to manufacturers and show them how to apply the WELMEC 7.2 guidelines. People need to know why these rules are there and to understand the thinking behind the regulations. This will make things much more accessible for the manufacturers and already at the development stage they will be able to take these requirements into account. I use many practical examples, which helps to make it both interactive and interesting for clients. I like to help people find the common thread in the document. This has also been a learning opportunity for me because now we have a better understanding as to why manufacturers make particular choices or come up with a particular design.’
What kind of problems do manufacturers come up against?
‘’One problem which many customers have to face is for example the introduction of software separation. This involves separating the software from the metrologically legal relevant component (i.e. the part that needs to be secure) from the non-legal component. If you ensure that the legal component is as compact as possible, this will give you as a manufacturer more flexibility in regard to the non-legal component. However this is something that needs to be specifically taken into account from the beginning of the design process. Another common problem is that many manufacturers do not understand exactly what ‘legally relevant’ means. Legally relevant does not refer only to the part that determines the measuring result. Everything that is controlled by legislation is legally relevant. For example, when there are requirements which state what must be visible on the display, this is legally relevant. This has no bearing on the measured value, yet the instrument could be rejected because of this. On the other hand people sometimes end up spending too much time on part of an instrument even though this is not necessary. For instance, if you include a second display on a measuring instrument, the second display is usually not legally relevant. Only the primary indication will be tested. In the training courses, I help manufacturers to define precisely what legally relevant will mean and how to secure the legally relevant part.’’
What kind of a role will WELMEC 7.2 play in the future?
“WELMEC is set to play an increasingly important role in the future. I can now predict that within a year’s time, WELMEC 7.2 will also apply to Non-Automatic Weighing Instruments (NAWIs that do not fall under the MID regulations). It would be of huge benefit to manufacturers if they can get timely advice from NMi regarding the regulations that will impact on their weighing instrument at the very start of the product development stage. This will reduce development costs and speed up the process from design to end product in accordance with the regulations. At the certification stage this will lead to fewer rejections and retests.”