IO-Link is playing a vital role in the development of smart factories and smart data. The communication standard enables digitization down to the sensor level. Recent growth figures demonstrate its impressive popularity. Nevertheless, many users still associate digitization with higher costs. This remains true even though IO-Link can significantly reduce hardware and installation costs, especially when used as a holistic system.
Important components
IO-Link has rapidly penetrated the market in the past few years. The number of IO-Link nodes reached 2.19 million in 2014, and had grown to 5.3 million by 2016. This exponential growth is expected to continue in the coming years. As a digital communication standard, IO-Link is designed to be a crucial component of the last mile of smart factories. However, this is precisely where the problem lies. Many users merely associate this technology with their undefined future applications. Sometimes they even believe that transformation requires replacing basic proximity switches with expensive devices. But the opposite is true. Furthermore, not all switches in an IO-Link system need to be equipped with IO-Link interfaces. In many applications, IO-Link has reduced costs from the outset, allowing customers to benefit immediately. Simultaneously, it lays the foundation for new applications that will emerge with Industry 4.0 .
Digital replaces analog
Few industries are as intimately connected to analog signal transmission as automation. Digital information requires significantly less bandwidth than analog information. Furthermore, digital transmission is far more stable and reliable. IO-Link offers bidirectional point-to-point connections up to 230.4 kBaud , ensuring reliable communication over unshielded standard cables. IO-Link sensors are typically cheaper than competing products using analog technology because they eliminate the need for digital-to-analog converters. This reduces wiring costs for users and also lowers the cost of the sensors themselves. Another advantage is that the IO-Link main channel is backward compatible with traditional binary sensors with one or two switch outputs. The spare channels remain largely available compared to the analog inputs.
Turck has supported IO-Link from the beginning and currently offers one of the most comprehensive IO-Link product portfolios. This includes a variety of sensors, connectivity technologies, and fieldbus and Ethernet I/O systems with IO-Link masters , with protection ratings of IP20 and IP67 .
From passive connection to Ethernet and IO-Link
In most applications, binary I/O signals (such as inductive proximity switch signals) represent the most commonly used signal type. Even today, these signals are often captured in the field by passive connectors (IP67) and connected to central or distributed I/O modules (IP20) via multi-core cables in a control cabinet . To save on equipment and cabling costs, a more modern approach is to use active distributed IP67 I/O modules in the field. These modules can capture signals as close as possible to the actuating switches and transmit them directly to higher-level controllers via Industrial Ethernet (or other fieldbuses). This eliminates the need for distributed modules in a control cabinet, allowing for a smaller form factor. An additional benefit is the lower cost of cabling via Industrial Ethernet. This architecture, using IP67 I/O modules to capture signals directly in the field, plays a significant role in automation, especially when only a few signals are captured in the field, such as in robotics.
IO-Link also reduces costs for high I/O density applications . A so-called I/O junction box can compress up to 16 additional signals and transmit them via IO-Link . An IO-Link master station with 4 or 8 ports can collect data from distances up to 20 meters away and transmit the data to the controller via a single Ethernet cable. In this case, users can achieve three cost savings: the I/O junction box is cheaper than industrial Ethernet modules; it uses unshielded standard cables instead of shielded Ethernet cables; and IO-Link requires only one cable for both data and power, eliminating the need for a separate power cable. Another advantage is that only individual IO-Link masters need IP addresses, not all I/O modules. Turck's TBIL I/O junction box (IP67) can transmit up to 16 I/O signals via an M12 circular connector with metal threads .
Turck supports its customers' journey toward Industry 4.0 through its extensive portfolio of IO-Link products.
Integrating the actuator into the overall IO-Link system
For a long time, it was believed that all future smart actuators or sensors would be based on Industrial Ethernet. However, current engineering practices have demonstrated the limitations of Ethernet in automation. Ethernet, with its transmission rates of 100 Mbit/s or even 1 Gbit/s and a minimum frame size of 64 bytes, is too demanding for many devices. Ethernet interfaces are also relatively expensive and generate a lot of heat. IO-Link , with its exceptional cost-effectiveness, can technically fill this gap. Although IO-Link is often positioned as a smart sensor interface, the technology was designed from the outset for communication between sensors and actuators. This gives it a key advantage over Ethernet: both power and communication are transmitted over a single cable.
The most typical example of a field device with an IO-Link interface is a valve manifold. IO-Link valves and manifolds are now available in the product portfolios of all major manufacturers . Complex connections using adapters with Sub-D multi-pin connectors can be replaced with inexpensive standard cables. Examples of actuator modules using IO-Link include gripper systems, motors, frequency converters with digital outputs, and I/O junction boxes. Turck's TBEN-L-8IOL IO-Link master is specifically optimized for actuator operation. Unlike other manufacturers, it can provide up to 4 amps of power through two ports. Users can particularly benefit from the possibilities offered by IO-Link , such as multi-segment indicator lights. Connecting more than two segments of indicator lights using digital multi-pin cables is very complex. However, IO-Link indicator lights , which can be configured with individual segment colors, audible signals, and various additional functions, can be easily wired and operated with a single standard cable. Turck's optical sensor partner, Banner Engineering's TL50 indicator light is available with IO-Link . Therefore, the configuration and number of indicator light elements are no longer limited by the associated wiring work. Users are therefore more likely to choose to use more than two signal segments. This allows for the display of more machine statuses, not just "OK" and "Error" . Different options are available for configuration and integration into higher-level systems. With the help of configuration tools, devices can initially be assigned via an IO-Link master, USB master, or USB adapter. Alternatively, configuration can also be done through functional modules within the controller. For example, this allows for modification of the device's configuration during runtime as part of a configuration file modification. The nature of higher-level networks such as Profinet or EtherNet/IP means that there are still no manufacturer-independent options available for directly configuring IO-Link devices through engineering systems. However, improvements are already being seen. In 2017 , the "IO-Link Integration – Profinet IO Version 2" specification defined a manufacturer-independent engineering interface for Profinet .
The TBEN-L and TBEN-S series IO-Link master modules feature simple IO-Link Device Integration (SIDI) functionality , enabling plug-and-play integration of Turck and Banner devices. All of the company's IO-Link devices are integrated into the site's GSDML file within the TBEN series IO-Link master module . This significantly simplifies setup. When the GSDML file is read via engineering software ( TIA Portal or other software) , all Turck devices are selected for specific port configurations. No further parameterization or programming is required.
IO-Link releases development resources
One of the main advantages of IO-Link is its independence from any fieldbus protocol. The sheer number of relevant fieldbus and industrial Ethernet protocols presents a real challenge for manufacturers of distributed field devices. Developing different device models for each protocol, maintaining them throughout their lifecycle, and providing the necessary support are all very costly. This also ties up human resources, preventing them from investing in future development and innovation. Therefore, some manufacturers have committed to completely migrating to the IO-Link interface and no longer integrating bus interfaces. They have delegated the integration of higher-level systems to the manufacturers of IO-Link masters. Thus, in this respect, IO-Link, by freeing up development resources, is also an engine of innovation.
Overall system cost-effectiveness
If the decision to switch to IO-Link is based on individual components, the IO-Link master module might be considered a disadvantage due to its indirect costs . However, if the system is considered holistically and changes to sensors, actuators, and I/O systems are evaluated, significant cost savings can be achieved using IO-Link . The cost savings of IO-Link become fully apparent when the time spent on wiring and cable assembly is also taken into account . Many Industry 4.0 scenarios that frequently involve connectivity using smart interfaces are unnecessary. However, IO-Link systems prepare users for these scenarios. More flexible sensor settings from the controller or queries for sensor data for predictive maintenance can be set up later. Not only are IO-Link devices crucial, but the functionality of the master module is also essential for the intelligent use of future systems. However, manufacturers' devices are constantly evolving, although communication standards remain consistent. The Turck IO-Link master module is housed in a multi-protocol I/O module, allowing parallel access via Modbus TCP and Profinet . This enables data transfer to higher-level I4.0 or IIoT systems such as SAP Pco , Microsoft Azure , or IBM Bluemix .
Outlook
The IO-Link product portfolio now offers all the necessary components for the cost-effective implementation of complete automation solutions. The latest events in the IO-Link industry demonstrate how IO-Link helps customers prepare for the future. The IO -Link security specifications make it possible to implement security concepts across all aspects of IO-Link in the future. The IO-Link industry is also developing specifications that allow access to IO-Link master modules and devices from higher-level I4.0 systems .
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