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Local perspectives on IO-Link, and its role in IIot

Four Profibus Australia members involved in IO-Link discuss the nature of IO-Link, its advantages, how it will help usher in the world of IIoT/Industry 4.0, and the challenges to adoption the industry faces.



The Industrial Internet of Things (IIoT) is the meeting point between technological progress and the drive within the process and manufacturing industry for ever increasing efficiency and transparency.

IIoT and Industry 4.0 proponents envision a world where production and process machines are able to communicate and cooperate with each other in increasingly sophisticated ways. Those who successfully embrace this technology will see increased visibility into their operations, greater efficiencies, less downtime, and have the option to automate an increasing number of operations, including changeovers, scaling and equipment reassignment.

But this will not be possible without a big increase in intelligence and data, which have to be derived from connected sensors and devices. The data flow will be both ways: sensors will provide the comprehensive data that the control system will use to create the bigger picture, but also taking on configuration instructions from the control system. Actuators, too, will accept digital instructions in order to act on operational requirements.

Michael Pitschlitz from IFM Efector, in his whitepaper titled “IO-Link – an integral part in the next industrial revolution known as Industry 4.0”, said that this will “change control systems architecture, system connectivity and sensors as we know it today.”

“Sensors are going to have to provide a lot more data than just a 4 to 20 mA or digital signal to the control system and/or system optimization software (MES),” he wrote. “In addition to the amount of data required from the sensor will be the ability to set the parameters of the sensor from the control system and/or system optimization software.”

Addressing the challenges of IIoT

This means many more devices can be expected to come online over the next few years. But because the industry has to work within existing conditions, it faces the following challenges:

  • the devices need be able to talk to each other using compatible protocols, even if they are from different manufacturers
  • the new devices and communication pathways need to work with existing Fieldbus and automation networks
  • ability to install and integrate large numbers of new devices into existing networks, without taking up a lot of time, money, or breaking the network

One of the key technologies that will help with these challenges is IO-Link. IO-Link (IEC 61131-9) is the first standardised technology for communication with sensors and actuators, using the standard 3-wire connection cable already used in industrial networks today. This enables point-to-point connection from the control platform right down to the sensors measuring the parameters, while making for a simple upgrade process within the Fieldbus/PLC layer.

Four Profibus Australia members are actively involved with IO-Link: Balluff, Siemens, IFM Efector and Phoenix Contact. We have reached out to key representatives from these companies for their thoughts on IO-Link.

Siemens: Enabling smarter sensors

Connecting sensors and actuators to automation systems is nothing new, of course. For a long time, the industry has wired up these systems, allowing the sensors and actuators to simply turn something on or off in an automation system.

According to Robert Geppert, Product Manager at Siemens, IO-Link brings with it the opportunity to do more than just sense whether something's on or off, or to turn something on and off.

“You might want to be able to re-parametise the sensor or the actuator on the fly from the automation system. IO-Link will let you do that.”

“For instance, with our motor starters, with IO-Link we're sensing whether they're supplying voltage or not, where you don't normally get that with conventional systems. So you're actually getting improved diagnostics by using IO-Link than you would using conventional wiring systems.”

A wire replacement system

That said, it is important not to overstate the role of IO-Link. According to Robert, IO-Link should not be considered a bus system. Rather, it is at the bottom end of the bus systems hierarchy, an option that simplified the wiring up of sensors and actuators.

“In terms of bus systems, at the top end is PROFINET which is our Ethernet networking system. Then below that level is PROFIBUS, which is an RS-485 bus system,” Robert explained.

“Below that are two options...IO-Link and AS-I Bus. Instead of hard wiring from automation system inputs and outputs to sensors and actuators, we use a system like AS-i Bus or IO-Link which simplifies that.”

These wire replacement systems still pass through the signals from sensors and the actuators, even while yielding simpler wiring.

While it is tempting to view IO-Link and AS-I as competing solutions, Robert says there is a place for both. Siemens, for example offers both options. IO-Link can handle service data, which AS-I cannot. However, AS-I works well for long-distance point-to-point communications.

“We use IO-Link inside the control cabinets, and AS-I for distribution between control cabinets,” Robert explained.



Balluff: IO-Link allows simpler integration of more devices

IIoT means a large wave of new devices and sensors will need to be connected to the system. But with traditional approaches to industrial control networks, connecting and configuring these new devices can be difficult or time consuming. According to Jim Wallace, National Marketing Manager at Balluff, IO-Link solves the problem.

“In the past if I wanted to connect to an RFID device, maybe an intelligent signal tower, each of those would have to have its own ProfiNet address on the network,” Jim explained.

IO-Link is structured so that only one ProfiNet node is required for an IO-Link master, which sits between the smart sensors/actuators and the fieldbus/PLC layer.

“One of the basic benefits of IO-Link is that we can attach multiple IO-Link enabled smart devices to a single network node...we can go from one IO-Link master to 8 or 16 different IO-Link enabled devices such as RFID readers or to standard IO blocks.”

Because of the modular nature of IO-Link system, it is easy to add devices to the system: adding an extra pressure senor or valve manifold, for example, can be done with minimal change in the PLC.

Disconnecting and reconnecting devices is also straightforward.

“Because it's a point to point communication, if we disconnect one device - maybe it's a changeover of an end effector on the robot - we don't lose the network.”

“You still have visibility that an IO device has been disconnected and then as soon as it's reconnected you can see that in the PLC.”

According to the Jim, IO-Link’s ability to parameterise devices over the link allows parameter changes to be done automatically in flexible processes.

“Rather than this being done manually by an operator changing a program, we can download all the parameters to all the different IO-Link devices just by a simple recipe change in the PLC.”

Simpler maintenance and replacement

Replacement of IO-Link devices is also relatively pain-free, with a fool-proof plug-and-play type mechanism.

“When an IO-Link device is connected to the IO-Link master, the master sends a wake-up call and the device replies with its identification data, manufacturer and part number et cetera. At that point the IO-Link master can automatically download information that's been set and saved to the new device, so there's no input from the PLC,” Robert explained.

Alternatively, it can pass on the device data to the PLC, which then determines if the device is the correct one. If it is, the PLC can call up a function block and download the parameterisation data to the new device. If not, the PLC can prompt the operator for action via the HMI.

Additionally, because IO-Link is just an expansion of the existing bus, and because it uses the standard three-core cable, no expensive proprietary cables and connectors are needed.

IFM Efector: IO-Link is a bridge in more ways than one

According to Jas Singh, Systems and Solutions Manager at IFM Efector, IO-Link is the bridge that allows machines to talk to machines and databases, enabling smarter sensors and communications between sensors, devices and systems.

But IO-Link is also a bridge that links the analogue past to present-day technology, and to the connected, digital future.

This perspective of IO-Link as a bridge between systems and between analogue and digital workflows is reflected in IFM Efector’s hardware and software systems.

“IFM has produced a whole range of modules which can smartly communicate to the PLCs and supply a whole lot of information. For sensors, our solutions can provide the traditional analogue information about the device, like the dielectric values,” explained Jas.

“So a normal digital device can actually act as an analogue device on IO-Link as well.”

IFM has also introduced a range of modules designed specifically to bridge IO-Link sensors with ERP systems, connecting the factory floor to the enterprise level systems and databases.

Phoenix Contact: Providing the communications pathway

Phoenix Contact provides the communication paths from the IO-Link sensors and actuators up through the Fieldbus systems into the control system, whatever that control system may be.

The company also provides IEC 61131-based control systems, which IO-Link is part of, allowing extra functionality to be read and obtained from sensors and actuators.

According to John Ortika, Product Manager at Phoenix Contact, the ability to derive service data and process data from devices opens up new possibilities for projects and platforms, an area of great interest for the process industry.

“You get extra service data from these sensors and actuators which allows the end user to have better visibility over their maintenance processes and also the data they get from these devices,” says John.

While IO-Link is seen primarily as a technology for the process industry, because it allows bus systems to quickly and easily integrate field device functionality, Phoenix Contact has also seen the technology being applied to the manufacturing industry.



Considerations about the uptake of IO-Link

IO-Link arrived as a technology in 2009, but inertia within the industry has meant limited take-up.

“Everyone has their standard drawings, their standard ways of wiring things up, and so it takes some time to convince them to do things differently...the benefits are easy to quantify, but you have to use different, IO-Link-enabled hardware in either your sensors or the actuators,” pointed out Robert Geppert of Siemens.

The good news, however, is that IO-Link is readily integrated into existing Profibus and Profinet systems. In fact, companies like IFM Efector say that they have been building IO-Link chips into their products for years.

“IFM has got 70 per cent of the sensory instrumentation market relating to IO-Link,” says Jas. “However, alot of these IO-Link instruments and sensors have been lying dormant, that is, they are in the field but not being used as IO-Link devices.”

With so many IO-Link devices already existing in factories, albeit “under-cover”, as interest in Industry 4.0 and IO-Link capabilities ramp up, IFM says many of its customers will be activating these IO-Link capabilities, at which point they will be able to exploit features IFM have built in to make integration easier.

“A lot of the modules produced by IFM have got specific GSD and GSD in the files for Siemens depending on the connection with PROFINET,” Jas said. “So depending on the sensor, you will be able to find all the information regarding that device on the GSD file, which makes the integration very easy.”

Balluff, too, is optimistic about the take-up of IO-Link, citing the open nature of the IO-Link consortium, which encourages interoperability between manufacturers.

This openness means different vendors can go to market with as wide or as narrow a range of IO-Link devices as they see fit, improving the availability and range of IO-Link products, increasing market momentum and thus boosting customers’ confidence in the technology.

On their part, Balluff provides a holistic range of options, with both IO-Link sensors and the connectivity technology stocked locally to respond to any customer needs.

Conclusion: A challenging but exciting new horizon

With IIoT, engineers will need to skill up accordingly. No longer are devices isolated from the rest of the system. Rather, as Robert Geppert from Siemens points out, engineers involved in sourcing new parts will need to consider the entire design philosophy of the automation system being integrated with the part.

An engineer looking into an IO-Link-enabled motor starter must, for example, consider not just the capabilities of the unit, but also the communications and how it will fit into an automation system.

“Engineers will need a higher degree of knowledge to be able to plan around the integration of the automation system.”

This investment into knowledge, information and connectivity, however, will usher in a new age of smart, flexible processes, and unprecedented visibility, automation and efficiency.



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