Shishir Rege is a Technical Sales Specialist, Controls Architectures at Balluff Inc. He brings over 19 years of experience in applying robotics and industrial automation technologies in diverse industries including automotive, packaging, aerospace, and medical. Shishir enjoys sharing his knowledge and passion for automation to solve today's automation challenges.
In the industrial automation space, inductive sensors have grown very popular , most commonly used for detecting the proximity of metal objects such as food cans, or machine parts. Inductive coupling, also known as non-contact connectors, uses magnetic induction to transfer power and data over an air gap.
While inductive couplers have many uses, one of the most beneficial is for replacing a traditional slip-ring mechanism. Slip-rings, also known as rotary connectors, are typically used in areas of a machine where one part rotates, and another part of the machine remains stationary, such as a turn table where stations on the indexing table need power and I/O, but the table rotates a full 360°. This set up makes standard cable solutions ineffective.
A slip ring could be installed at the base of the table, but since they are electromechanical devices, they are subject to wear out. And unfortunately, the signs for wearing are not evident and often it is only a lack of power that alerts workers to an issue.
An inductive coupling solution eliminates all the hassle of the mechanical parts. With non-contact inductive coupling, the base of a coupler could be mounted at the base of the table and the remote end could be mounted on the rotating part of the table.
Additionally, slip rings are susceptible to noise and vibration, but because inductive couplers do not have contact between the base and the remote, they do not have this problem.
Inductive couplers are typically IP67-rated, meaning they are not affected by dirt or water, or vibrations, and most importantly, they are contact free so no maintenance is necessary.
In the last two blogs we discussed about Lean operations and reducing waste as well as Selecting right sensors for the job and the environment that the sensor will be placed. Anytime a sensor fails and needs a replacement, it is a major cause of downtime or waste (in Lean philosophy). One of the key benefits of IO-Link technology is drastically reducing this unplanned downtime and replacing sensors with ease, especially when it comes to measurement sensors or complex smart sensors such as flow sensors, continuous position monitoring sensors, pressure sensors, laser sensors and so on.
When we think about analog measurement sensor replacement, there are multiple steps involved. First, finding the right sensor. Second, calibrating the sensor for the application and configuring its setpoints. And third, hope that the sensor is functioning correctly.
Most often, the calibration and setpoint configuration is a manual process and if the 5S processes are implemented properly, there is a good chance that the procedures are written down and accessible somewhere. The process itself may take some time to be carried out, which would hold up the production line causing undesired downtime. Often these mission critical sensors are in areas of the machine that are difficult to access, making replacing then, let alone configuring, a challenge.
IO-Link offers an inherent feature to solve this problem and eliminates the uncertainty that the sensor is functioning correctly. The very first benefit that comes with sensors enabled with IO-Link is that measurement or readings are in engineering units straight from the sensor including bar, psi, microns, mm, liters/min, and gallons/min. This eliminated the need for measurements to be scaled and adjusted in the programming to engineering units.
Secondly, IO-Link masters offer the ability to automatically reconfigure the sensors. Many manufacturers call this out as automatic device replacement (ADR) or parameter server functionality of the master. In a nutshell, when enabled on a specific port of the multi-port IO-Link master, the master port reads current configuration from the sensor and locks them in. From that time forward, any changes made directly on the sensor are automatically overwritten by these locked parameters. The locked parameters can be accessed and changed only through authorized users. When the time comes to replace the sensor, there is only one step that needs to happen: Find the replacement sensor of the same model and plug it in. That’s it!
When the new sensor is plugged-in, the IO-Link master automatically detects that the replacement sensor does not have the correct parameters and automatically updates them on the sensor. Since the readings are directly in the units desired, there is no magic of scaling to fiddle with.
It is also important to note, that in addition to the ADR feature, there may be parameters or settings on the sensors that alert you to possible near-future failure of the sensor. This lets you avoid unplanned downtime due to sensor failure. A good example would be a pressure sensor that sends an alert (event) message indicating that the ambient temperature is too high or a photo-eye alerting the re-emitted light value is down close to threshold – implying that either the lens is cloudy, or alignment is off.
To learn more about IO-Link check out our other blogs.
In press shops or stamping plants, downtime can easily cost thousands of dollars in productivity. This is especially true in the progressive stamping process where the cost of downtime is a lot higher as the entire automated stamping line is brought to a halt.
Many strides have been made in modern stamping plants over the years to improve productivity and reduce the downtime. This has been led by implementing lean philosophies and adding error proofing systems to the processes. In-die-sensing is a great example, where a few inductive or photo-eye sensors are added to the die or mold to ensure parts are seated well and that the right die is in the right place and in the right press. In-die sensing almost eliminated common mistakes that caused die or mold damages or press damages by stamping on multiple parts or wrong parts.
In almost all of these cases, when the die or mold is replaced, the operator must connect the on-board sensors, typically with a multi-pin Harting connector or something similar to have the quick-connect ability. Unfortunately, often when the die or mold is pulled out of the press, operators forget to disconnect the connector. The shear force exerted by the movement of removing the die rips off the connector housing. This leads to an unplanned downtime and could take roughly 3-5 hours to get back to running the system.
Another challenge with the multi-conductor connectors is that over time, due to repeated changeouts, the pins in the connectors may break causing intermittent false trips or wrong die identification. This can lead to serious damages to the system.
Both challenges can be solved with the use of a non-contact coupling solution. The non-contact coupling, also known as an inductive coupling solution, is where one side of the connectors called “Base” and the other side called “Remote” exchange power and signals across an air-gap. The technology has been around for a long time and has been applied in the industrial automation space for more than a decade, primarily in tool changing applications or indexing tables as a replacement for slip-rings. For more information on inductive coupling here are a few blogs (1) Inductive Coupling – Simple Concept for Complex Automation Part 1, (2) Inductive Coupling – Simple Concept for Complex Automation Part 2
For press automation, the “Base” side can be affixed to the press and the “Remote” side can be mounted on a die or mold, in such a way that when the die is placed properly, the two sides of the coupler can be in the close proximity to each other (within 2-5mm). This solution can power the sensors in the die and can help transfer up to 12 signals. Or, with IO-Link based inductive coupling, more flexibility and smarts can be added to the die. We will discuss IO-Link based inductive coupling for press automation in an upcoming blog.
Some advantages of inductive coupling over the connectorized solution:
Since there are no pins or mechanical parts, inductive coupling is a practically maintenance-free solution
Additional LEDs on the couplers to indicate in-zone and power status help with quick troubleshooting, compared to figuring out which pins are bad or what is wrong with the sensors.
Inductive couplers are typically IP67 rated, so water ingress, dust, oil, or any other environmental factor does not affect the function of the couplers
Alignment of the couplers does not have to be perfect if the base and remote are in close proximity. If the press area experiences drastic changes in humidity or temperature, that would not affect the couplers.
There are multiple form factors to fit the need of the application.
In short, press automation can gain a productivity boost, by simply changing out the connectors to non-contact ones.
As manufacturers move toward Industry 4.0 and the Industrial Internet of Things (IIoT), common communication platforms are needed to achieve the next level of efficiency boost. Using common communication platforms, like Time-Sensitive Networking (TSN), significantly reduces the burden of separate networks for IT and OT without compromising the separate requirements from both areas of the plant/enterprise.
TSN is the mother of all network protocols. It makes it possible to share the network bandwidth wisely by allocating rules of time sensitivity. For example, industrial motion control related communication, safety communication, general automation control communication (I/O), IT software communications, video surveillance communication, or Industrial vision system communication would need to be configured based on their time sensitivity priority so that the network of switches and communication gateways can effectively manage all the traffic without compromising service offerings.
If you are unfamiliar with TSN, you aren’t alone. Manufacturers are currently in the early adopter phase. User groups of all major industrial networking protocols such as ODVA (CIP and EtherNet/IP), PNO (for PROFINET and PROFISAFE), and CLPA (for CC-Link IE) are working toward incorporating TSN abilities in their respective network protocols. CC-Link IE Field has already released some of the products related to CC-Link IE Field TSN.
With TSN implementation, the current set of industrial protocols do not go away. If a machine uses today’s industrial protocols, it can continue to use that. TSN implementation has some gateway modules that would allow communicating the standard protocols while adding TSN to the facility.
While it would be optimal to have one universal protocol of communication across the plant floor, that is an unlikely scenario. Instead, we will continue to see TSN flavors of different protocols as each protocol has its own benefits of things it does the best. TSN allows for this co-existence of protocols on the same network.
IO-Link is a point-to-point communication standard [IEC61131-9]. It is basically a protocol for communicating information from end devices to the controller and back. The beauty of this protocol is that it does not require any specialized cabling. It uses the standard 3-pin sensor cable to communicate. Before IO-Link, each device needed a different cable and communication protocol. For example, measurement devices needed analog signals for communication and shielded cables; digital devices such as proximity sensors or photo eyes needed 2-pin/3-pin cables to communicate ON/OFF state; and any type of smart devices such as laser sensors needed both interfaces requiring multi-conductor cables. All of these requirements and communication was limited to signals.
With IO-Link all the devices communicate over a standard 3-pin (some devices would require 4/5 pin depending if they need separate power for actuation). And, instead of communicating signals, all these devices are communicating data. This provides a tremendous amount of flexibility in designing the controls architectures for the next generation machines.
IO-Link data communication can be divided into 3 parts:
Process data: This is the basic functionality of the sensor communicated over cyclical messages. For example, a measurement device communicating measurement values, not 4-20mA signals, but the engineering units of measurement.
Parameter data: This is a cyclic messaging data communication and where IO-Link really shines. Manufacturers can add significant value to their sensors in this area. Parameter data is communicated only when the controller wants to make changes to the sensor. Examples of this include changing the engineering units of measurement from inches to millimeters or feet, or changing the operational mode of a photoelectric sensor from through-beam to retro-reflective, or even collecting capacitance value from a capacitive sensor. There is no specific parameter data governed by the consortium — consortium only focuses on how this data is communicated.
Event data: This is where IO-Link helps out by troubleshooting and debugging issues. Event messages are generated by the sensor to inform the controller that something has changed or to convey critical information about the sensor itself. A good example would be when a photoeye lens gets cloudy or knocked out of alignment causing a significant decrease in the re-emitted light value and the sensor triggers an event indicating the probable failure. The other example is the sensor triggering an event to alert the control system of a high amperage spike or critical ambient temperatures. When to trigger these events can be scheduled through parameter data for that sensor.
Each and every IO-Link device on the market offers different configurations and are ideally suited for various purposes in the plant. If inventory optimization is the goal of the plant, the buyer should look for features in the IO-Link device that can function in different modes of operation such as a photo eye that can operate as through-beam or retro-reflective. On the other hand, if machine condition monitoring is the objective, then he should opt for sensors that can offer vibration and ambient temperature information along with the primary function.
In short, IO-Link communication offers tremendous benefits to operations. With options like auto-parameterization and cable standardization, IO-Link is a maintenance-friendly standard delivering major benefits across manufacturing.
While fieldbus solutions utilize sensors and devices with networking ability, they come with limitations. IO-Link provides one standard device level communication that is smart in nature and network independent. That enables interoperability throughout the controls pyramid, making it the most suitable choice for smart manufacturing.
IO-Link offers a cost effective solution to the problems. Here is how:
IO-Link uses data communication rather than signal communication. That means the communication is digital with 24V signal with high resistance to the electrical noise signals.
IO-Link offers three different communication modes: Process communication, Diagnostic communication (also known as configuration or parameter communication), and Events.
Process communication offers the measurement data for which the device or sensor is primarily selected. This communication is cyclical and continuous in nature similar to discrete I/O or analog communication.
Diagnostic communication is a messaging (acyclic) communication that is used to set up configuration parameters, receive error codes and diagnostic messages.
Event communication is also acyclic in nature and is how the device informs the controller about some significant event that the sensor or that device experienced.
IO-Link is point-to-point communication, so the devices communicate to the IO-Link master module, which acts as a gateway to the fieldbus or network systems or even standard TCP/IP communication system. So, depending on the field-bus/network used, the IO-Link master may change but all the IO-Link devices enjoy the freedom from the choice of network. Power is part of the IO-Link communication, so it does not require separate power port/drop on the devices.
Every open IO-Link master port offers expansion possibilities for future integration. For example, you could host an IO-Link RFID device or a barcode reader for machine access control as a part of a traceability improvement program.
As technology advances at a faster pace and the world becomes flatter, manufacturing operations are generally focused on efficient production to maximize profitability for the organization. In the new era of industrial automation and smart manufacturing, organizations are turning to data generated on their plant floors to make sound decisions about production and process improvements.
Smart manufacturing improvements can be divided roughly into six different segments: Predictive Analytics, Track and Trace, Error Proofing, Predictive Maintenance, Ease of Troubleshooting, and Remote Monitoring.To implement any or all of these improvements requires interoperable systems that can communicate effectively and sensors and devices with the ability to provide the data required to achieve the manufacturer’s goals. For example, if the goal is to have error free change-overs between production cycles, then feedback systems that include identification of change parts, measurements for machine alignment changes, or even point of use indication for operators may be required. Similarly, to implement predictive maintenance, systems require devices that provide alerts or information about their health or overall system health.
Traditional control system integration methods that rely heavily on discrete or analog (or both) modes of communication are limited to specific operations. For example, a 4-20mA measurement device would only communicate a signal between 4-20mA. When it goes beyond those limits there is a failure in communication, in the device or in the system. Identifying that failure requires manual intervention for debugging the problem and wastes precious time on the manufacturing floor.
The question then becomes, why not utilize only sensors and devices with networking ability such as a fieldbus node? This could solve the data and interoperability problems, but it isn’t an ideal solution:
Most fieldbuses do not integrate power and hence require devices to have separate power drops making the devices bulkier.
Multiple fieldbuses in the plant on different machines requires the devices to support multiple fieldbus/network protocols. This can be cost prohibitive, otherwise the manufacturer will need to stock all varieties of the same sensor.
Several of the commonly used fieldbuses have limitations on the number nodes you can add — in general 256 nodes is capacity for a subnet. Additional nodes requires new expensive switches and other hardware.
IO-Link provides one standard device level communication that is smart in nature and network independent, thus it enables interoperability throughout the controls pyramid making it the most suitable choice for smart manufacturing.
We will go over more specific details on why IO-Link is the best suited technology for smart manufacturing in next week’s blog.
In the first part of this series “Demystifying Class A and Class B Type IO-Link Ports” we discussed the two different types of IO-Link master ports and pointed out how they differ in operation and applications. The point of that blog was to ensure that when we choose one over the other, what is the opportunity cost of that decision.
In my recent blog, part #2 in this series, “Not all IO-Link Masters are Born Equal!“, we explored that even when multiple vendors provide or call out their IO-Link master, they are different in the implementation of features and functions they offer. IO-Link is IO-Link! It is a standard for communication but other features that accompany the communication differentiates how they behave; for example- sensor only master, hybrid master, and architecture backbone master.
In this blog, we will focus on various implementations of Port Type A (or Class A) and how they add varying degrees of value to your applications.
Implementation #1: Figure 1 below depicts the guts (electrical connections) of one of the three implementations of the IO-Link Class A master port. Two key things to notice here:
The power coming into the IO-Link master port is only device power. There is no output power with this implementation. The reason that it is designed like this is to only integrate sensor inputs.
Pin 1 and Pin 3 provide the device power and ground (common) to the IO-Link device, pin 4 is IO-Link communication. Pin 2 works as an input only for digital sensors like photo-eyes or prox switches. Basically, this port can be split to use one IO-Link sensor (pins 1, 3 and 4) and one standard ON/OFF sensor (pins 1,3, and 2).
Another alternate of this implementation is that some vendors may have another IO-Link connection on Pin 2. So, it serves to add 2 IO-Link devices off the same port. Unfortunately, I am not an expert to say whether this is according to the specification or not.
The Pros: Low power consumption and simplifies integrating smart sensors.
The Cons: By definition, a control system has both inputs and outputs – controlling “something” based on sensory inputs and logic. This implementation provides semi-standard implementation to the controls architecture. IO-Link promises unified communication across the plant floor not half of the plant floor. Characteristics of this type of master port would be max output current of about 250-300mA per port and about 2A per module (rated for up to 4A, if its carries UL).
Implementation #2: This implementation is a slight variation of the sensor only port (Implementation #1 above). It is achieved by adding an output capability for pin 2 on each port- shown in figure 2 below. It is important to note that although each port has output capability on pin 2, the output power is shared with the device power for the port. It implies that, in case of E-stop situations, where shutting off power to the valves/solenoids connected to pin 2 or an IO-Link device that requires an output power, the entire device power will be shut-off. Basically, the state of the device connected to pin 2 and state of IO-Link devices connected on pin 4 will be lost or requires more elaborate approach (programming, testing and validation) in the controls side to handling these types of safety situations.
This type of implementation is commonly found on hybrid IO-Link master’s Class A (type A) port implementation.
The Pros: Flexibility to use pin 2 for input or output – standardized approach to all devices.
The Cons: Lack of ability to control the output power separate from the device power – causing variety of controls approaches (lots of precautions) when incorporating machine safety.
Implementation #3: This implementation offers the most flexibility in designing the controls architecture that utilizes IO-Link. Figure 3 depicts the implementation below. In this case, the device power, as prior approaches, comes from pin 1 and pin 3 but pin 2 uses a separate power for output. The pin 2 on each of these ports can be used for input, output or to provide separate output power to the IO-Link devices. It is important to note that although pin 2 offers output power separate from the device power, the common/ground for this power is still tied to pin 3. The output power is separate but not isolated, like in the Class B port implementation discussed in the blog “Demystifying Class A and Class B Type IO-Link Ports“.
The two key advantages with this approach are: 1) High amperage output can be used from pin 2 to control valves or solenoids by splitting the port, and 2) IO-Link devices such as valve terminals or configurable I/O hubs that require output power can be connected with standard 4 pole cables without needing additional power cables or connectors.
This does appear very similar to implementation 2 where output power can be provided as well. The key difference is that since the output power comes from a different power line, it is not shared with the device power — as you know, amperage reduces when you have parallel circuits, so implementation 2 is subject to that principle whereas implementation #3 is not.
Another benefit with this approach is that a safety relay can be placed on the power going to pin 2 because the output power for the entire module is separate. That means in case of E-stop situations, the output power can be shut off without harming the device power. This eliminates the need for elaborated controls planning as the device state is maintained throughout the operation. After recovering from an E-stop, the valves and all other outputs go back to their original state. This significantly simplifies your controls architecture, offers standardized approach to cabling and provides unified interface for all devices.
To learn more about Balluff’s implementation of IO-Link masters please visit www.balluff.com.
IO-Link as a standard for device level communication has been around for over a decade. It has started gaining huge momentum in the Americas with 60-70% growth in IO-Link integration in 2017 alone (awaiting official numbers from the IO-Link consortium). Due to this huge market demand for IO-Link, there has been an insurgence of IO-Link masters with features and functionality that is dazzling machine builders and end users alike.
While IO-Link as a communication platform is a standard (IEC 61131-9), the added features and functions leave some machine builders confused on how to reap benefits of these different masters that are around. Some machine builders have a thought process of “Hey, vendor A is selling an IO-Link master and vendor B is also selling an IO-Link master – they are both IO-Link so, why should I pay more?” These machine builders are choosing the lower cost options without realizing what they are missing out on – and sometimes getting disgruntled about the technology itself. On the other hand, some machine builders are spending too much time in measuring and testing a variety of masters – wasting precious time and materials to identify what fits best for their solution. With this blog post and my next, I am hoping to add some clarity on how to detect differences quickly amongst the masters and make a decision that is best suitable for the applications at hand.
IO-Link started out as a standard of communications for smart sensors with a focus to eliminate variety of different interfaces on the plant floor- but since its inception it has manifested itself to be much more than simple sensor integration. It has also gained significance as a backbone for enabling Industry 4.0 or IIoT. So, let’s review different types of IO-Link masters.
The very first thing machine builders have to do is determine whether the IO-Link master should be IP20 (in cabinet) implementation or IP65-67-69 rated (machine mounted) implementation.
The machine mounted version makes sense as it is suitable for most industrial environments. The IP20 version may be desirable if the machine is operating in extreme environments or experiences continuous changes in temperature, humidity and other factors.
With machine mount masters:
It is easier to debug the system with onboard diagnostics availability
Eliminates wiring and terminates hassle and saves time and money during the machine building process.
If the IP20 master is your choice, then there isn’t a major difference between vendor A and vendor B IO-Link masters. The difference could appear based on whether the IO-Link master is a part of a larger system or stand-alone module connected to the machine controller through one of the fieldbus or network gateway. One more thing to note about IP20 masters is they are meant for connecting 3-pin IO-Link devices only. If you want to use architectural benefits of having added Vaux (separate output power) then using IP20 masters becomes complicated and quickly becomes expensive.
If the initial features of machine mounted masters are appealing to you, then there are a few more decisions to be made. The machine mounted IO-Link masters (for simplicity let’s call them IP67 Masters) range from “sensor only” integration capable masters to the ones that have the ability to become a backbone for flexible modular controls architecture. There are primarily three different types of masters as shown below in the chart and they differ based on the power routing capabilities and power handling capabilities.
Since the inception of the Class (or Type) A and Class (or Type) B ports in the IO-Link specifications, there have been several new IO-Link devices and IO-Link masters introduced to the market. This has caused a lot of confusion about when and where to use Class A and Class B IO-Link masters and devices.
Before getting into the details of Class A vs. Class B, I would like to address one question that I get asked quite often: are Class B master ports safety-rated? The answer is no. Just like any other network I/O modules (with the exception of the Safety I/O modules), any type of IO-Link master (whether it is Class A, Class B or mixed) is not safety rated. If the block is safety-rated, I am certain that the manufacturers of these blocks will kindly let you know. So, we just busted the first myth about Class B ports. Side note: the IO-Link Consortium just released a specification for IO-Link Safety. At the time of this posting (Oct. 2017), there are no IO-Link masters on the market that are safety rated, even when the IO-Link master ports exist alongside Safety I/O parts on the same block.
For IO-Link communication, only pins 1, 3 and 4 have significance. The implementations of pin 2 and 5 is where Class A and Class B ports differ and with that, the advantages and disadvantages of the uses for these ports.
Clearly, with the wiring diagrams above, a Class A port offers more flexibility in terms of additional I/O count and in some cases high-amperage outputs to drive high-current devices such as valves. We will discuss the detailed power routing and application flexibility of Class A ports in a later blog.
With Class B ports, Pin 2 and Pin 5 are tied to a separate power source and cannot really be used as I/O. Pin 5, the ground for output power, is separated from pin 3, the ground for device power. Actuation devices, such as valve banks, that are now offered on IO-Link could utilize separate output power that can be turned off through safety relays. Technically, this separation of power is possible with Class A ports as well, but it is inherent with Class B ports.
A word of caution when implementing I/O architectures with Class B masters: since the commons for device power and output power are isolated at the master, the power fed to this device should be isolated at the source as well to keep the isolation intact. That means, the power supplies feeding the power to these devices should be isolated.
Another question that I get asked frequently reveals another myth about Class B master ports: do Class B master ports offer any extra power than Class A ports? Again the answer is no. Class B does not mean extra power or the ability to provide more power. It simply means output power with isolated commons. What leads to that thinking is that on several IO-Link masters in the market, the outputs available on pin 2 of Type A ports have lower amperage ratings, because in most cases the output power is shared or drawn from the same source that feeds device power. There will be more discussion about this in my next blog!
A third interesting question is, can you plug Class A IO-Link devices into Class B master ports? In most cases there is no problem doing this as a true IO-Link Class A device is only a 3 pin device using pins 1,3, and 4 shown above. So as long as pin 2 of the device does not exist or is not being used for any purpose, it is possible to use Class A devices with Class B ports. Caution: several manufacturers make sensors that can be used in IO-Link mode as well as analog or digital mode and the implementation may have more than 3 pins. In these circumstances, you will need to use a 3-pole cable to keep the device unharmed or the pin 2 of the type B port that always has +24V going through may damage or disrupt the sensor.
Meanwhile, I hope this blog helped provide some clarity on Class A and Class B ports.