- AS-Interface
- Interview
Interview with Bernhard Wiedemann: New ASi-5 Safety products expand application range
ASi MASTER NEWS: The future is always an origin story. This applies as well to the implementation of functional safety using AS-Interface. How would you describe the topic of safety in the developmental context of ASi-3 and ASi-5?
Bernhard Wiedemann: When in 1990 AS-Interface was initiated by several companies as a system for networking sensors and actuators, we were technologically still far from being able to use bus systems in general for functional safety, nor was the desire there. This did not change until around ten years later, so that functional safety was then integrated into ASi subsequently. But at the same time is was a milestone for the fieldbus itself in terms of being able to collect the signals from simple safety sensors in the field and send them together with non-safe signals through the ASi profile cable. This made AS-Interface the first system to make safety technology practical on a fieldbus. Which in turn was a significant factor in driving the success of ASi
In contrast, safety was a fundamental consideration in all the technical developments that have led to ASi-5, making possible the most efficient integration possible of even complex safety sensors and applications. Work on the ASi-5 Safety Stack, such as the transmission mechanisms and protocols, was therefore already concluded when the actual ASi-5 specification was presented at SPS 2018. And at the latest since TÜV NORD certification of the ASi-5 Safety Monitor Reference Firmware for use in ASi-5 Safety Monitors and ASi-5 Safety devices in January 2019 ASi-5 Safety has been de facto applicable in actual products.
ASi MASTER NEWS: Does this mean that safety products for ASi-5 will come to market faster than with the previous ASi generations?
Bernhard Wiedemann: Absolutely. Before the end of this year – which is barely three years after the new technology standard was introduced – we will introduce the first ASi-5 products for functional safety.
ASi MASTER NEWS: What will happen in the future with ASi Safety at Work now that the first ASi-5 Safety products are being brought to market? Will ASi-3 Safety be discontinued in favor of ASi-5 Safety?
Bernhard Wiedemann: We are proceeding under the assumption that ASi Safety at Work and ASi-5 Safety will both be available over the next years. Approximately 80 percent of the safety-related applications are less complex, often requiring only one single two-channel safe signal to be transmitted – for example from an E-Stop button. And for this ASi Safety at Work is still perfect. In these scenarios ASi-5 Safety is neither superior nor less expensive. But things do look different when multiple safe signals or a combination of safe and non-safe signals need to be transmitted. Then ASi-5 Safety with its high speed and large data bandwidth as well as its expanded diagnostics is the optimal supplement to ASi Safety at Work – as is the case already for ASi-3 in standard applications..
ASi MASTER NEWS: What does this mean for the user?
Bernhard Wiedemann: Like ASi-3 and ASi-5 in the non-safety area, ASi Safety at Work and ASi-5 Safety run completely in parallel on the same profile cable. This means you can use both safe and non-safe signals from all the ASi generations in the network at the same time. The benefit to the user is ASi-5 Safety also provides the simple and cost-effective installation technology of AS-Interface. There are mainly two reasons for this: for one, ASi-5 Safety lets you use one address for up to 16 safe bits and other non-safe signals. In addition, and perhaps even more important for the user, ASi-5 Safety modules with one or two safe inputs and multiple non-safe I/O points cost virtually the same as comparable I/O modules that are non-safe only.
ASi MASTER NEWS: ASi-5 Safety is finished and certified. And represents an expansion to ASi Safety at Work, especially in terms of the data bandwidth and presence of both safe and non-safe signals. Doesn’t this mean that it now provides all the options for integrating IO-Link Safety devices as well in the future?
Bernhard Wiedemann: Correct. ASi-5 technology will allow you to collect safe IO-Link signals in the field cost-effectively and efficiently. And if they are available, the great data bandwidth of ASi-5 will enable even high-performance IO-Link Safety devices to be integrated into ASi networks without any restrictions. ASi-5 Safety, which is already fully developed and certified, then represents an ideal shuttle for integrating safe IO-Link Safety devices into higher automation levels where safety functions are also implemented. We are good to go.
ASi MASTER NEWS: Let’s summarize: ASi Safety at Work can handle safety-related standard applications, whereas ASi-5 Safety will also enable realization of highend applications with IO-Link Safety. Does this mean that mixed systems are the optimum solution?
Bernhard Wiedemann: In my view this will be one of the trends. If you only need to process individual safe signals such as an E-Stop button, ASi-3 Safety will remain your first choice both in terms of cost and technology. Where there is greater density of safe and non-safe signals in an application – regardless of whether you are dealing with individual signals or complex safety sensors – ASi-5 Safety represents a perfect supplement to ASi Safety at Work both economically and technologically.
ASi MASTER NEWS: Of course this presumes that the corresponding modules are available. What is the situation at Bihl+Wiedemann in this respect?
Bernhard Wiedemann: In terms of technology we are quite far along – thanks also to the fact that we have had the specification and certification from TÜV for three years already. We are currently working on an ASi-5 Safety gateway as well as a module with two safe 2-channel inputs and 12 self-configuring I/Os for non-safe signals. This module allows, for instance, the connection of a control panel with several light buttons, an E-Stop button and a safe key switch to ASi at extremely low cost. We will be introducing both the ASi-5 Safety gateway and the I/O module at this year’s SPS. Plus, we are already working on additional ASi-5 Safety modules in IP67, IP20 and as a circuit board version. And as is always the case at Bihl+Wiedemann, I fully expect that unique customer requirements will result in additional new products. A look at our portfolio and specialized offerings tells you how driven we also are by our customers.
