What is IO-Link? A Simple Explanation of the Universal Networking Standard

Famed physicist Albert Einstein once said, “If you can’t explain it simply, you don’t understand it well enough.” When the topic of IO-Link comes up, whether a salesperson or technical expert is doing the explaining, I always find it’s too much for the layman without a technical background to understand. To simplify this complex idea, I’ve created an analogy to something we use in our everyday lives: highways.  

Prior to the Federal Highway Act of 1956, each individual state, determined the rules of its state highway routes. This included everything from the width of the roads to the speed limits and the height of bridge underpasses — every aspect of the highways that were around at the time. This made long-distance travel and interstate commerce very difficult. It wasn’t until 1956 and the passage of President Eisenhower’s Federal Highway Act, that the rules became standard across the entire United States. Today, whether you’re in Houston, Boston or St. Louis, everything from the signage on the road to the speed limits and road markings are all the same. 

Like the standardization of national highway system, the IO-Link Consortium standardized the rules by which devices in automation communicate. Imagine your home as a controller, for example, the roads are cables, and your destination is a sensor. Driving your car to the store is analogous to a data packet traveling between the sensor and the controller.  

You follow the rules of the road, driving with a license and abiding by the speed limits, etc. Whether you’re driving a sedan, an SUV or a semitruck, you know you can reach your destination regardless of the state it’s in. IO-Link allows you to have different automation components from different suppliers, all communicating in sync unlike before, following a standard set of rules. This empowers the end user to craft a solution that fits his or her needs using sensors that communicate using the protocols set by the IO-Link Consortium. 

IO-Link Wireless – IO-Link with Even Greater Flexibility

In a previous blog entry, I discussed IO-Link SPE (Single-Pair Ethernet). SPE, in my opinion, has two great strengths compared to standard IO-Link: cable length and speed. With cable lengths of up to 100 meters and speed of 10 Mbps, compared to 20 meters and max baud rate of 230.4 Kbps, what could be out of reach?

Robots. We see robots with cabling routed either through the arm itself or tracking along the outside of the arm. Every time the robot moves, we know the conductors within these cables are deteriorating. Is there another “tool” in the IO-Link Consortiums special interest groups that can aid us? Yes, IO-Link Wireless.

Basics

Let cover the basics quickly. The architecture will contain a wireless master, wireless in terms of the connection to the IO-Link devices and wireless IO-Link devices. There is no real change to the physical connection of the IO-Link master to the controls system, just the elimination of cabling between the IO-Link master and IO-Link devices. It is perfect for a robot application.

Power

Wireless concepts are not new. When I saw the specification to IO-Link Wireless, the first question that came to mind was about powering the IO-Link devices. Luckily, we are in an age of batteries. and with the evolution of the EV market, battery technology has come a long way. This eliminates my concerns for low power devices. IO-Link was designed to bring more data back from our sensor and actuator devices, so IO-Link is perfectly suited to pass along battery diagnostics; low or failing batteries diagnostics/information should be readily available for a control and/or IIOT system. IO-Link devices with high current consumptions will still need to be wired to a power system.

Density of IO-Link Devices per IO-Link Master

Currently, with wired IO-Link masters, the most common configuration is eight IO-Link ports (i.e., 8 IO-Link devices can be connected), with the rare 16 port version. There is a huge advantage to wireless here within the IO-Link specification. One wireless IO-Link Master can contain up to 5 transmission tracks, where each transmission track can communicate to up to 8 IO-Link devices. That is 40 wireless IO-Link devices per wireless IO-Link master. There are a lot of details within the IO-Link Wireless specification that I will not even begin to discuss, but to go one layer more; within a physical area that the specification calls a “cell”, three wireless IO-Link Masters can exist, giving us a total of 120 wireless IO-Link devices occupying a designated area. We all know that wireless will come with a larger price tags, but at least there is a tradeoff of fewer masters (wired = 15 master, wireless = 3, for 120 devices).

Distance and Speed

I started this blog entry referencing the two strengths of SPE — length and speed. Here is where there is a great difference between Wireless and SPE IO-Link exists. If a wireless master is using one transmission track, the 8 IO-Link devices can be 20 meters away, equaling the standard wired architecture of IO-Link. As soon as we enable another transmission track, the maximum distance drops to 10 meters. The minimum transmission cycle time is 5 milliseconds. Still, I believe the pros of IO-Link Wireless outweigh the length restrictions.

Non-wireless IO-Link devices

Within the specification, there is the ability to have wireless bridges in the architecture. These bridge modules would contain a master IO-Link port to communicate to the standard IO-Link device, and then on the other side communicate to the wireless IO-Link master as a IO-Link Wireless device.

Applications

Obviously, robot end-efforts are the first to come to mind for a wireless solution. Food, beverage and medical applications also comes to mind. By eliminating the cabling, there is less surface area where contaminants can exist. Also, it could be used in inductive race ways, where a “pallet” moves along an inductive rail, which is supplying power, but I may not want to put a controller on each pallet. Lastly, IO-Link Wireless could be a good solution in any place where cabling is flexed and bent.

Conclusion

Does standard wired IO-Link fit every application? No. Does Single-Pair Ethernet and IO-Link Wireless? No. Thankfully, the IO-Link Consortium is giving us multiple methodologies to create our IO-Link architectures, where one application may need to encompass all three. For those applications that require fewer or the elimination of cables, the IO-Link Wireless solution can fit this space. For further information on the IO-Link specification, go to the consortium’s website at: IO-Link.com.

Continuous and Exacting Measurements Deliver New Levels of Quality Control

Quality control has always been a challenge. Going back centuries, the human eye was the only form of quality verification. Hundreds of years ago metal tools like calipers were introduced to allow for higher repeatability compared to the human eye. This method is very cumbersome and is only an approximation based off a sample of the production, potentially allowing faulty products to be used or shipped to the customer.

What is the best solution by today’s standards? By scanning the product at all times! Using continuous measurements reduces or even eliminates the production of faulty products and allows for consistent and repeatable production. This used to be an impossible task for small products, but with the invention of the laser and CMOS(Complementary Metal Oxide Semiconductor) imaging sensors, extremely small measurements can be achieved. How small? In an industrial environment, measuring 0.3 mm components with a resolution of 10 micrometers is absolutely attainable. Using special optics to spread the beam across a window will allow for 105 mm of measuring range and up to 2 meters distance between the transmitter (laser spread light) and receiver (CMOS sensor).

Traditionally these sensor systems have one or two analog outputs and have to be scaled in the control system to be usable. These values are repeatable and accurate once scaled but there has to be a better way. IO-Link to the rescue!

IO-Link brings an enormous amount of information and flexibility to configuration. Using IO-Link will also reduce the amount of wiring and analog input cards/hubs required. The serial communications of IO-Link also reduce overall costs thanks to its use of standard cables, as opposed to shielded cables. This allows for 20 meter runs over a standard double ended M12 cables without information loss or noise injection. Another benefit to going with IO-Link is the drastic increase in bits of resolution. Analog input cards and analog input hubs tend to provide between 10-16 bits of resolution, whereas IO-Link has the ability to pass two measurements via process data in the form of dual 32 bit resolution arrays as well as more information about the status of the sensors.

With IO-Link, you also gain the ability to use system commands like restarting the device, factory reset, signal normalization, reset maintenance interval, and device discovery. With this level of technology and resolution, quality control can be taken to down to the finest details.

The Right Mix of Products for Recipe-Driven Machine Change Over

The filling of medical vials requires flexible automation equipment that can adapt to different vial sizes, colors and capping types. People are often deployed to make those equipment changes, which is also known as a recipe change. But by nature, people are inconsistent, and that inconsistency will cause errors and delay during change over.

Here’s a simple recipe to deliver consistency through operator-guided/verified recipe change. The following ingredients provide a solid recipe-driven change over:

Incoming Components: Barcode

Fixed mount and hand-held barcode scanners at the point-of-loading ensure correct parts are loaded.

Change Parts: RFID

Any machine part that must be replaced during a changeover can have a simple RFID tag installed. A read head reads the tag in ensure it’s the correct part.

Feed Systems: Position Measurement

Some feed systems require only millimeters of adjustment. Position sensor ensure the feed system is set to the correct recipe and is ready to run.

Conveyors Size Change: Rotary Position Indicator

Guide rails and larger sections are adjusted with the use of hand cranks. Digital position indicators show the intended position based on the recipes. The operators adjust to the desired position and then acknowledgment is sent to the control system.

Vial Detection: Array Sensor

Sensor arrays can capture more information, even with the vial variations. In addition to vial presence detection, the size of the vial and stopper/cap is verified as well. No physical changes are required. The recipe will dictate the sensor values required for the vial type.

Final Inspection: Vision

For label placement and defect detection, vision is the go-to product. The recipe will call up the label parameters to be verified.

Traceability: Vision

Often used in conjunction with final inspection, traceability requires capturing the barcode data from the final vials. There are often multiple 1D and 2D barcodes that must be read. A powerful vision system with a larger field of view is ideal for the changing recipes.

All of these ingredients are best when tied together with IO-Link. This ensures easy implantation with class-leading products. With all these ingredients, it has never been easier to implement operator-guided/verified size change.

How Condition Monitoring has Evolved and Its Role in IIoT

In recent years, as IIoT and Industry 4.0 have become part of our everyday vocabulary, we’ve also started hearing more about condition monitoring, predictive maintenance (PdM) and predictive analytics. Sometimes, we use these terms interchangeably as well. Strictly speaking, condition monitoring is a root that enables both predictive maintenance and predictive analytics. In today’s blog we will brush up a little on condition monitoring and explore its lineage.

Equipment failures have been around since the beginning of time. Over the years, through observation (collecting data) and brute-force methods, we learned that from time-to-time every piece of equipment needs some TLC. Out of this understanding, maintenance departments came to existence, and there we started having experts that could tell based on touch, smell and noise what is failing or what has gone wrong.

Figure 1: Automation Pyramid

Then we started automating the maintenance function either as a preventative measure (scheduled maintenance) or through some automated pieces of equipment that would collect data and provide alerts about a failure. We proudly call these SCADA systems – Supervisory Control and Data Acquisition. Of course, these systems did not necessarily prevent failures, but help curtail them.  If we look at the automation pyramid, the smart system at the bottom is a PLC and all the sensors are what we call “dumb sensors”. So, that means, whatever information the SCADA system gets would be filtered by the PLC. PLCs were/have been/ and are always focused on the process at hand; they are not data acquisition equipment. So, the data we receive in the SCADA system is only as good as the PLC can provide. That means the information is primarily about processes. So, the only alerts maintenance receives is when the equipment fails, and the process comes to a halt.

With the maintenance experts who could sense impending failures becoming mythological heroes, and  SCADA systems that cannot really tell us the story about the health of the machines, once again, we are looking at condition monitoring with a fresh set of eyes.

Sensors are at the grass root level in the automation pyramid, and until the arrival of IO-Link technology, these sensors were solely focused on their purpose of existence; object detection, or measurement of some kind. The only information one could gather from these sensors was ON/OFF or a signal of 4-20mA, 0-10V, and so on. Now, things are different, these sensors are now becoming pretty intelligent and they, like nosy neighbors, can collect more information about their own health and the environment. These intelligent sensors can utilize IO-Link as a communication to transfer all this information via a gateway module (generally known as IO-Link master) to whomever wants to listen.

Figure 2: IO-Link enabled Balluff photo-eye

The new generation of SCADA systems can now collect information not only from PLCs about the process health, but also from individual devices. For example, a photo-eye can measure the intensity of the reflected light and provide an alert if the intensity drops beyond a certain level, indicating a symptom of pending failure. Or a power supply inside the cabinet providing an alert to the supervisory control about adverse conditions due to increase temperature or humidity in the cabinet. These types of alerts about the symptoms help maintenance prevent unplanned downtime on the plant floor and make factories run more efficiently with reduced scrap, reduced down-time and reduced headaches.

Figure 3: The Next Generation Condition Monitoring

There are many different condition monitoring architectures that can be employed, and we will cover that in my next blog.

Is IO-Link with Single Pair Ethernet the Future?

20 meters.

That is the maximum distance between an IO-Link master port and an IO-Link device using a standard prox cable.  Can this length be extended?  Sure, there are IO-Link repeaters you can use   to lengthen the distance, but is there an advantage and is it worth the headache?

I hope you like doing some math, because the maximum distance is based on the baud rate of the IO-Link device, the current consumption of the IO-Link device and finally the cross section of the conductors in the cabling.  Now throw all that into a formula and you can determine the maximum distance you can achieve.  Once that is calculated, are you done? No.  Longer cables and repeaters add latency to the IO-Link data transfer, so you may need to slow down the IO-Link master’s port cycle time due to the delay.

Luckily, there is a better and easier solution than repeaters and the sacrifice of the data update rate — Single Pair Ethernet (SPE).

SPE is being discussed in all the major communication special interest groups, so it makes sense that its being discussed within the IO-Link Consortium.  Why?  A couple of key factors: cable lengths and updated speeds.  By using SPE, we gain the Ethernet cable length advantage. So, instead of being limited to 20 meters, your IO-Link cabling could stretch to 100 meters!  Imagine the opportunities that opens in industrial applications.  It is possible that even longer runs will be achievable.  With 10 Mbit/s speed, to start, the update rate between IO-Link devices and the IO-Link master could be less than 0.1 millisecond.

Latency has been the Achilles heal in using IO-Link in high-speed applications, but this could eliminate that argument. It will still be IO-Link, the point-to-point communication protocol (master-to-device), but the delivery method would change. Using SPE would require new versions of IO-Links masters, with either all SPE ports or a combination of SPE and standard IO-Link ports. The cabling would also change from our standard prox cables to hybrid cables, containing a single twist Ethernet pair with two additional conductors for 24 volts DC.  We may even see some single channel converts, that convert standard IO-Link to SPE and vice versa.

There likely would have been pushback if this was discussed just five or ten years ago, but today, with new technology being released regularly, I doubt we see much resistance. We consumers are ready for this. We are already asking for the benefits of SPE and IO-Link SPE may be able to provide those advantages.

For more information, visit www.balluff.com.

Improve OEE, Save Costs with Condition Monitoring Data

When it comes to IIOT (Industrial Internet of Things) and the fourth industrial revolution, data has become exponentially more important to the way we automate machines and processes within a production plant. There are many different types of data, with the most common being process data. Depending on the device or sensor, process data may be as simple as the status of discrete inputs or outputs but can be as complex as the data coming from radio frequency identification (RFID) data carriers (tags). Nevertheless, process data has been there since the beginning of the third industrial revolution and the beginning of the use of programmable logic controllers for machine or process control.

With new advances in technology, sensors used for machine control are becoming smarter, smaller, more capable, and more affordable. This enables manufacturers of those devices to include additional data essential for IIOT and Industry 4.0 applications. The latest type of data manufacturers are outputting from their devices is known as condition monitoring data.

Today, smart devices can replace an entire system by having all of the hardware necessary to collect and process data, thus outputting relative information directly to the PLC or machine controller needed to monitor the condition of assets without the use of specialized hardware and software, and eliminating the need for costly service contracts and being tied to one specific vendor.

A photo-electric laser distance sensor with condition monitoring has the capability to provide more than distance measurements, including vibration detection. Vibration can be associated with loose mechanical mounting of the sensor or possible mechanical issues with the machine that the sensor is mounted. That same laser distance sensor can also provide you with inclination angle measurement to help with the installation of the sensor or help detect when there’s a problem, such as when someone or something bumps the sensor out of alignment. What about ambient data, such as humidity? This could help detect or monitor for moisture ingress. Ambient pressure? It can be used to monitor the performance of fans or the condition of the filter elements on electrical enclosures.

Having access to condition monitoring data can help OEMs improve sensing capabilities of their machines, differentiating themselves from their competition. It can also help end users by providing them with real time monitoring of their assets; improving overall equipment efficiency and better predicting  and, thereby, eliminating unscheduled and costly machine downtime. These are just a few examples of the possibilities, and as market needs change, manufacturers of these devices can adapt to the market needs with new and improved functions, all thanks to smart device architecture.

Integrating smart devices to your control architecture

The most robust, cost effective, and reliable way of collecting this data is via the IO-Link communication protocol; the first internationally accepted open, vendor neutral, industrial bi-directional communications protocol that complies with IEC61131-9 standards. From there, this information can be directly passed to your machine controller, such as PLC, via fieldbus communication protocols, such as EtherNET/Ip, ProfiNET or EtherCAT, and to your SCADA / GUI applications via OPC/UA or JSON. There are also instances where wireless communications are used for special applications where devices are placed in hard to reach places using Bluetooth or WLAN.

In the fast paced ever changing world of industrial automation, condition monitoring data collection is increasingly more important. This data can be used in predictive maintenance measures to prevent costly and unscheduled downtime by monitoring vibration, inclination, and ambient data to help you stay ahead of the game.

Use IODD Files with IO-Link for Faster, Easier Parameterization

Using IO-Link allows you to get as much data as possible from only three wires. IO-Link communicates four types of data: device data, event data, value status, and process data. Value status data and process data are constantly sent together at a known rate that is documented in each device’s manual and/or data sheet. Device and event data stores your device parameters and allow for the ultimate flexibility of IO-Link devices. Since the IO Device Description (IODD) files contain each device’s full set of parameters, using them saves you from the need to regularly refer to the manual.

Commissioning IO-Link devices

When first using an IO-Link device, the standard process data will be displayed. To maximize the functionality of the device, parameters can be accessed and, in some cases, changed.  The available parameters for any IO-Link device are located in at least two places: the device’s manual and the device’s IODD file.  The manual will display the required hexadecimal-based index and sub-index addresses to point your controller’s logic, which will allow the user to change/monitor parameters of the device during operation.  This is great for utilizing one or two parameters.

However, some devices require a large number of parameter adjustments to optimize each device per application.  Using IODD files to commission devices can be faster and make it easier to select and change parameters, because all available parameters are included in the XML based file.  Certain masters and controllers have the ability to store these IODD files, further improving the integration process.  Once the IODD files are stored and the device is plugged into an IO-Link port, you can choose, change, and monitor every parameter possible.

Where can I find IODD files?

The IO-Link consortium requires all IO-Link device manufacturers to produce and post the files to the IODD finder located on io-link.com.  Most IO-Link device manufacturers also provide a link to the IODD file on the product’s web page as well as the IO-Link.com site.

Industry 4.0: What It Is and How It Improves Manufacturing

Industry 4.0 is a common buzzword that is thrown around along with IIoT and Process visualization but what does that mean and how is it integrated into a manufacturing process? Industry 4.0 refers to the fourth industrial revolution. The first dealing with mechanization and the use of steam and water power, the second referring to mass production using assembly lines and electrical power, and the third referring to automated production and the use of computers and robots. Industry 4.0 takes us a step beyond that to smart factories that include automation and machine learning. Again, buzzwords that can be hard to visualize.

A commonplace example of this would be self-driving cars. They are autonomous because they don’t need a person operating them and they take, in real time, information about their surroundings and use that to determine a course of action. But how can this type of technology affect a manufacturing process?

Industry 4.0 requires data to be analyzed. This is where IO-Link comes into play. With IO-Link, you are able to get information from a sensor more than than just an output signal when it detects a part. A photoelectric sensor is a good example of this. The basic way a photoelectric sensor works an output is given depending on the amount of light being received. If the sensor happens to be in a dirty/dusty environment, there could be dirt collecting on the lens or floating in the air which effects the amount of light being received. An IO-Link (smart) sensor can not only fire an output when detection occurs but can give information about the real time gain of the sensor (how much light is being received). If the gain drops below a certain amount because of dirt on the lens or in the air, it can send another signal to the controller indicating the change in gain.

Now that we have more data, what are we going to do with it?

We now have all of this data coming from different parts of the machine, but where does it go and what do we do with it? This is where process visualization comes into play. We are able to take real time data from a machine and upload it to a database or system that we can monitor outside of the plant floor. We can know if a machine is running properly without having to physically see the machine. The information can also give us indications about when something might fail so preventative maintenance can take place and reduce downtime.

As more manufacturing processes are becoming automated, machines are becoming more and more complex. A machine might be needed to run 6-7 different lines rather than just 1 or 2 which can involve things like tool change or settings changes. Then, more checks need to be in place, so the right process is running for the right part. Industry 4.0 is how we are able to gather all this information and use it to increase efficiency and productivity.

Adding Smart Condition Monitoring Sensors to Your PLC Control Systems Delivers Data in Real Time

Condition monitoring of critical components on machines delivers enormous benefits to productivity in a plant.  Rather than have a motor, pump, or compressor unexpectedly fail and the machine be inoperable until a replacement part is installed, condition monitoring of those critical pieces on the machine can provide warning signs that something is about to go terribly wrong. Vibration measurements on rotating equipment can detect when there is imbalance or degrade on rolling bearing elements. Temperature measurements can detect when a component is getting overheated and should be cooled down. Other environmental detections such as humidity and ambient pressure can alert someone to investigate why humidity or pressure is building up on a component or in an area. These measurement points are normally taken by specific accelerometers, temperature probes, humidity and pressure sensors and then analyzed through high end instruments with special analysis software. Typically, these instruments and software are separate from the PLC controls system. This means that even when the data indicates a future potential issue, steps need to be taken separately to stop the machine from running.

Using smart condition monitoring sensors with IO-Link allows these measured variables and alarms to be available directly onto the PLC system in real time. Some condition monitoring sensors now even have microprocessors onboard that immediately analyze the measured variables. The sensor can be configured for the measurement limit thresholds of the device it’s monitoring so that the sensor can issue a warning or alarm through the IO-Link communications channel to the PLC once those thresholds have been hit. That way, when a warning condition presents itself, the PLC can react immediately to it, whether that means sending an alert on a HMI, or stopping the machine from running altogether until the alarmed component is fixed or replaced.

Having the condition monitoring sensor on IO-Link has many advantages. As an IEC61131-9 standard, IO-Link is an open standard and not proprietary to any manufacturer. The protocol itself is on the sensor/actuator level and fieldbus independent. IO-Link allows the condition monitoring sensor to connect to Ethernet/IP, Profinet & Profibus, CC-Link & CC-Link IE Field, EtherCAT and TCP/IP networks regardless of PLC. Using an IO-Link master gateway, multiple smart condition monitoring sensors and other IO-Link devices can be connected to the controls network as a single node.

The picture above shows two condition monitoring sensors connected to a single address on the fieldbus network. In this example, a single gateway allows up to eight IO-Link condition monitoring sensors to be connected.

Through IO-Link, the PLC’s standard acyclic channel can be used to setup the parameters of the measured alarm conditions to match the specific device the sensor is monitoring. The PLC’s standard cyclic communications can then be used to monitor the alarm status bits from the condition monitoring sensor.  When an alarm threshold gets hit, the alarm status bit goes high and the PLC can then react in real time to control the machine. This relieves the burden of analyzing the sensor’s condition monitoring data from the PLC as the sensor is doing the work.