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What is IO-Link?

Paul Sarcinello
Posted by Paul Sarcinello on Jul 15, 2021 10:00:00 AM

Whether you're new to the world of machine automation, or an industry veteran, the implementation and advancement of IO-Link is shaping the future. This is the first article in a series dedicated to IO-Link and how it is transforming the industry, so naturally, we're starting with the basics. First, let's break down what IO-Link is and why you should care about it.

artificial-intelligence-3382521_1920Jump to Section:

The Basics

5 Biggest Advantages

IO-Link in Practice

How to get started with IO-Link


Resources and Info

The Basics


io-link-techAt its core, IO-Link is an industrial communication method used between sensors and actuators, an IO-Link master control unit, and a higher-level controller like an HMI (Human Machine Interface) or PLC (Programmable Logic Controller). It is a short distance (20 meters or less), wired (or wireless), digital, and bi-directional networking standard per IEC 61131-9. The most critical adjective in that sentence is probably "bi-directional," as IO-Link allows for IO-Link capable sensors and actuators to communicate numerous data points back to the master controller, and ultimately, the user.

Previously, devices operating at the field level, like sensors, valves, switches, and encoders, worked in the dark, (hopefully) performing their active duties but not reporting any information back. However, advancements in the industry like IIoT (industrial internet of things) and Industry 4.0 (automation and intelligent machines in manufacturing) require data to be abundant, readily available, recordable, and shareable, and manually collecting all of that data from traditional machines is a tedious and cumbersome task. That's where IO-Link steps in as the standard way for field devices and controllers to communicate, making it easier to collect, track, and store device data.

Once configured, each IO-Link master has complete access, visibility, and control over every IO-Link compatible device to which it is connected. The IO-Link master controller essentially acts as a middle-man between sensors and actuators and the higher-level controller, but not all controllers use the same communication language. As the network standard, IO-Link integrates with all of the various industrial protocols that PLC's use, such as Ethernet, Profibus, and other Fieldbus networks. IO-Link converters can even bring an analog-type field device into an IO-Link system! Note that IO-Link is not just another Fieldbus but a point-to-point communication protocol. Its open standard can integrate into virtually any Fieldbus or automation system. 


The Five Biggest Advantages Of IO-Link


1. Data Availability

To run a smooth operation and optimize maintenance and production schedules, you need data. IO-Link provides data routinely and automatically (cyclic data) and command (acyclic data). There are three primary types of data that IO-Link transmits:

  • Process Data: The real-time data of the field level device's operations (temperature, distance, etc.), often sent cyclically (automated routinely) as scheduled by the user. 
  • Service Data: Information about the device itself, such as the type of field device, the manufacturer, the operating parameters, serial number, configuration, etc. Also called Device Data
  • Event Data: These are notifications like error messages and maintenance warnings, often about dirty sensors or overheating. These send acyclically (not scheduled) as events occur. 

All of this data is available in real-time for monitoring and recorded over time to analyze trends.


2. Virtually Eliminate Unplanned Downtime

science-in-hd-i4ABHj811N0-unsplashMany operations function with broad maintenance routines that become lax and put on the back burner as their list of reactive problems grows. With IO-Link, as all of the data talked about above is monitored and analyzed correctly, maintenance becomes proactive, predictable, and preventable. In addition, maintenance is now performed based upon status and need and often in scheduled downtime before a problem happens, as data trends and real-time alerts help show devices nearing the end of their lifespan. 


3. Easy Device Replacement

Because of all the stored service data (device data) on the IO-Link master, replacing faulty devices is as easy as plugging them in. It no longer requires highly skilled and experienced personnel to configure replaced devices. The IO-Link master will ensure that the replacement component is the correct replacement and instantly configures to the previous device's specifications. The "plug and play" and diagnostic/troubleshooting functionalities of IO-Link mean that any downtime event that does occur will quickly recover. 


4. Easy Wiringwires

An underrated benefit of IO-Link is that it often simplifies and reduces cabling. In addition, it uses unshielded three or five-wire cables, meaning it is more cost-effective with fewer types of cord sets required.


5. Remote Monitoring and Configuration

IO-Link brings the ability to remotely monitor and change device parameters through the master control system; changes can even while the machine is still running!
This is invaluable in manufacturing operations with frequent product changeover (they make many different products), as IO-Link can make transitions between products seamless, saving significant amounts of downtime. It also means that operations do not need as much skilled staffing on-site, as problems are identified and resolved from anywhere (especially since technicians don't need to configure devices anymore). 


What Does IO-Link Look Like In Practice?


Let's look at what IO-Link does in an everyday setting. For example, let's say a photoelectric sensor just failed on a production line.

Without IO-Link, a failure like this is entirely unpredictable. The sensor functioned adequately and was "routinely checked." Still, because of random factors and unknown deterioration, the failed sensor has shut down the entire line for an undetermined amount of time. It will now take time (which is money in manufacturing) to identify the problem, find which sensor is faulty, replace it, and then appropriately configure it. If the sensor was faulty, potential product defects need to be accounted for.

With IO-Link, the IO-Link master can continuously monitor the condition and performance of any connected IO-Link sensor. As performance metrics are monitored over time, a slow decline in sensor performance is detected (previously "unknown deterioration"). It now gets scheduled to be checked and/or replaced during routine maintenance procedures, avoiding the stoppage entirely. When technicians replace the faulty sensor, the IO-Link master already has the configuration settings of the previous sensor saved, so the new one is instantly correctly integrated. 


If you're ready to get started using IO-Link, check out our next article,
How to Get Started with IO-Link.

How To Get Started with IO-Link



IO-Link is the standard communication protocol that helps users get vital information about their machine devices. In addition, IO-Link makes critical data and device controls remotely available and makes maintenance a breeze.

All IO-Link capabilities result in overall reduced costs, improved machine availability, and increased process efficiency. Operations that are severely impacted by unplanned or extended downtimes and/or experience frequent changeover have the most to gain from IO-Link's advantages. Still, operations of all shapes and sizes can benefit!

Look out for the next IO-Link article, which will talk about essential devices that are IO-Link capable, so don’t forget to subscribe to our blog!


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Topics: Automation, IoT, Explainers

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