Wireless to the last mile

13 September 2021

Alexander Weber discusses the beneficial relationship that IO-Link Wireless and 5G can offer in industrial applications.

Wireless applications have become an indispensable part of our everyday lives with users no longer being concerned about how these wireless connections are established and whether they are stable. It is only when the connection is interrupted that we take a closer look at the technology.

In industrial environments, however, wireless technology is still met with reservations, primarily due to the need for high machine availability.

However, with wired solutions machine communications cannot be physically tested, which means that a potential failure quickly becomes a challenge. Collisions of the packets with relevant information from other packets in the same frequency band, as well as shielding/reflection of the nodes by components in the immediate vicinity, for example, can occur. This can result in a communication breakdown and a possible control malfunction after just a few. Traditionally, such problems have been difficult to prevent using, often proprietary, wireless technologies. This has also hindered the adoption of wireless components in industrial automation. 

However, it is in precisely these situations where that the call for wireless applications is getting louder today. What is needed are industrial standards that offer users the greatest possible flexibility, diversity and scalability. Many wireless networks cannot meet the requirements for reliability, device density, installation effort and physical dimensions, which is why they are rarely used. 

A recently study from HMS Networks, with a representative survey of 50 international industry professionals, (https://www.hms-networks.com/industrial-iot-solutions/5G/ready) found that wireless applications for remote monitoring and remote control of equipment are already being used by over 54% of the respondents to the study, while 48% of respondents also claimed that they are positive about 5G and would like to use this technology instead of the unreliable Wi-Fi and its various industrial derivatives. 

In the context of 5G (Ultra Reliable and Low Latency Communication), however, another standardised wireless technology – called IO-Link Wireless – should also be mentioned. Both standards in coexistence create a great added value and potentiate the each other's respective areas of application.

IO-Link Wireless is a standard that was defined specifically for factory automation. It provides a reliable, real-time and deterministic protocol for control systems in industrial factory automation. It adds wireless transmission links to the classic wired cables in industrial control applications, increasing mobility and flexibility and elevating plant communications to the master level of automation.

In parallel, companies are starting to market various 5G-based products and services as part of the fourth industrial revolution. In this context, the 5G transformation is designed to take several years, as production deployments require stable specifications, production-grade implementation, and supportive ecosystems before widespread availability can be achieved.

Implementation considerations
If a wireless communication solution is to be implemented for a machine, several key factors must be taken into consideration: 

• Output
• Latency
• Application
• Physical dimensions
• Range
• Costs
• Availability of the frequency spectrum

Indeed, both technologies have their justifications. They cover various application areas within industrial automation technology. As a glance at the automation pyramid shows, they also address very different types of nodes in each case. 

IO-Link Wireless is primarily intended for field devices in factory automation that already communicate via IO-Link. It is therefore also a solution that can be spatially limited – used selectively and scaled to transmit the signals of switching and measuring sensors, but also of simpler actuators. Process data of < 2 bytes are processed and forwarded. Since these devices are often lower cost and used in large numbers, the total cost of a system often determines the success of the new technology. In addition, the devices communicate directly with the controller via a node (IO-Link master), which makes a stable and continuous connection from master to device essential, which is also a high requirement for time-critical applications. IO-Link Wireless is based on the standardised IO-Link technology (IEC 61131-9) and therefore meets these requirements while offering the same high communication stability (Packet Error Rate 10-9) as the wired version. In addition, it is a flexible and cost-efficient solution that can be embedded in an existing infrastructure with the previously used sensors and actuators with little effort.

5G, on the other hand, was designed as a communication medium for field nodes with greater bandwidth. It is a comprehensive network infrastructure designed for a higher level of communication. For example, this technology is not designed to serve a selective application area due to the licensing costs and the investment in infrastructure. It will typically be found within the automation pyramid at the higher field level, where Ethernet-based nodes are also used, involving, for example, communication between the controller and camera systems, servo motors, fieldbus modules or even data transmission from robots to a gateway. These devices are typically installed in smaller quantities and, due to their complexity, are also in a different price range, which is why the additional costs for the 5G infrastructure of a complete manufacturing environment are less significant. 

Because both technologies serve different use cases, they are very well suited to be used within a combined system. The different frequency bands are also not expected to interfere with each other, even if they are not directly compatible. A fieldbus module could act as the hub of both technologies, communicating downward via IOLW and upward via 5G. IO-Link Wireless can therefore fully coexist with any 5G network. These networks do not contradict each other as 5G focusses on high-end applications with higher data throughput. 

Alexander Weber is head of the IO-Link Wireless Working Group at Profibus International.

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