Faster, More Flexible, Just as Simple: ASi-5
Automation companies first joined forces in 1990 to create a system for networking sensors and actuators. The resulting AS‑Interface technology has long since established itself in industrial automation as a cost-effective and efficient wiring technology. Now a new generation of the standard is being developed: ASi‑5. The AS‑Interface user organization is introducing the new standard at the 2018 SPS IPC Drives trade fair. Dr. Thomas Sebastiany, Director of the Systems Business Unit at Pepperl+Fuchs and board member for the AS‑Interface user organization, spoke with us about upgrading the current AS‑Interface standard.
Dr. Sebastiany, why is it time for the next generation of AS‑Interface?
The current AS‑Interface standard, ASi‑3, still feels like a recent development. However, we have noticed that market requirements have changed a lot in the last few years. When AS‑Interface development began in the early 1990s, the initial goal was to transmit simple switching signals to a control system with minimal effort and as cost-effectively as possible. Nowadays, other aspects play a much more significant role. Users expect systems to perform more complex tasks, such as recording and transferring detailed diagnostic and parameter data. Intelligent sensors and actuators are responsible for an increasing number of control functions in distributed systems. We, too, must align our system with these developments to meet the changing needs of customers. Seven well-known automation companies, including Pepperl+Fuchs, have joined forces to develop the new standard, which we are calling ASi‑5.
What will ASi‑5 change for users compared to the previous AS‑Interface standard?
First, we want to emphasize the fact that the new generation will keep all of the tried-and-tested benefits of AS‑Interface. In other words, AS‑Interface will continue to be a simple and cost-effective wiring, data communication, and power solution based on the familiar flat cable with reverse polarity protection and simple piercing technology. With ASi‑5, we will increase the data bandwidth and create more flexibility for communication. The current AS‑Interface occasionally reaches its limit when transmitting comprehensive diagnostic and parameter data. The data that is increasingly being generated in the Industry 4.0 era and concepts like predictive maintenance cannot be transferred at the volume and speed necessary for them to be used efficiently. With ASi‑5, we want to significantly enhance the existing standard and raise the process data bandwidth from a maximum of 4 to 16 bits per slave. The new specification also allows IO-Link sensors to be integrated into AS‑Interface, making ASi‑5 suitable for future requirements.
What are the specific advantages of these changes for users?
The higher data bandwidth and faster communication with cycle times as low as 1.2 ms will make it possible to consider this technology for data-intensive and time-critical applications in the future. Thanks to new transmission methods—time-division multiplexing and frequency-division multiplexing—customers also have the flexibility to adapt their communication systems and implement high-speed or high data bandwidth communication networks. Users benefit from better performance and greater flexibility.
Can you speak more about the new transmission methods?
With time-division multiplexing, you can determine how often or in what cycle a slave communicates with the master. ASi‑5 allows us to implement what are known as subcycles, each lasting 1.2 ms. Four subcycles account for one ASi‑5 cycle. The customer now has the option to determine whether a slave updates its data in each subcycle—so every 1.2 ms—or only in every fourth subcycle, for instance. If a slave is set to communicate in every subcycle, the maximum number of slaves that can be connected to a segment will be reduced. Users can therefore choose whether to connect 24 slaves that communicate every 1.2 ms, or 96 slaves that update every 5 ms. Frequency-division multiplexing refers to transport channels (TC), which each process 16 bits. One of these transport channels is made available to each ASi‑5 slave so that it can transfer data. However, frequency-division multiplexing also allows a slave to use up to four of these channels to transfer more data. Each individual slave can be easily combined with time-division and frequency-division multiplexing to transfer up to 32 bytes per slave. It is worth noting that the new method can be easily combined with the established, trusted ASi-3 transmission method on the same flat yellow cable. This backward compatibility with ASi‑3 was a key requirement when development of the ASi‑5 specification began.
With ASi-5, we will increase the data bandwidth and create more flexibility for communication.
Surely the increased data bandwidth and communication flexibility contradicts the basic principle of an easy-to-use AS‑Interface?
Usability is and will remain simple. Just like before, the ASi‑5 master controls all communication within the AS‑Interface network and transmits the information via higher-level fieldbuses such as PROFINET and EtherNet/IP to a central control system or via an Edge Gateway to the cloud. At the same time, the ASi‑5 master checks whether the slaves actually wired in the field match the planned slaves. The master generates an error message if an error is detected. This feature even makes it easier to commission a facility since wiring errors can be reliably detected. The technical subtleties of frequency-division multiplexing and time-division multiplexing are built into the new ASi‑5 ASICs, and everything stays the same for the customer.
Are any ASi-5 devices already available?
ASi‑5 products are currently under development. This is why the partner companies wanted to announce ASi‑5 at the 2018 SPS IPC Drives show, given its importance as a trade fair for automation technology. Doing so gives our users an opportunity to explore the benefits of ASi‑5 in their own applications and requirements. In addition, user organization members believe that it is important to not simply present customers with finished products but to invite them to share their wishes and suggestions for the new ASi generation. Ultimately, we want the new generation to adapt to changing requirements, so it is essential for us to communicate with those who are actually using the technology. With this in mind, we are looking forward to interacting with people interested in the new standard, whether in person at the AS‑Interface booth, at SPS IPC Drives 2018, or afterward.
What will happen to existing AS‑Interface devices when ASi‑5 products become available?
The greatest advantage of ASi‑5 is that it’s completely backwards compatible. The introduction of ASi‑5 devices will have no negative impact on existing AS‑Interface networks. Users can operate both ASi‑5 devices and ASi‑3 devices on an ASi‑5 combi master at the same time. This feature is part of our efforts to make enhancements and conversion to ASi‑5 as easy as possible for customers. After all, the new ASi‑5 generation is designed to continue meeting customers’ needs while also delivering the same familiar advantages.
Can you disclose anything about how development is going at Pepperl+Fuchs?
For Pepperl+Fuchs, one of the founders of the ASi‑5 development community, the enhancement of AS‑Interface is an extremely important project, and we will continue to drive it forward. This is why we are also working hard to develop new products. But we do not want to rush things or present something that has not yet been meticulously scrutinized and industrially tested and "hardened." Such an approach would not fulfill our high quality standards. We have therefore set the goal of launching an appealing Pepperl+Fuchs ASi‑5 product family within the next two years. By 2019, an addressing device with a modern smartphone-based operating concept will be available for all project partners. Of course, customer-specific ASi-5 development projects may be underway before then.