Are machine diagnostics overburdening our PLCs?

In today’s world, we depend on the PLC to be our eyes and ears on the health of our automation machines. We depend on them to know when there has been an equipment failure or when preventative maintenance is needed. To gain this level of diagnostics, the PLC must do more work, i.e. more rungs of code are needed to monitor the diagnostics supplied to the sensors, actuators, motors, drives, etc.

In terms of handling diagnostics on a machine, I see two philosophies. First, put the bare bones minimum in the PLC. With less PLC code, the scan times are faster, and the PLC runs more efficiently. But this version comes with the high probability for longer downtime when something goes wrong due to the lack of granular diagnostics. The second option is to add lots of diagnostic features, which means a lot of code, which can lessen downtime, but may throttle throughput, since the scan time of the PLC increases.

So how can you gain a higher level of diagnostics on the machine and lessen the burden on the PLC?

While we usually can’t have our cake and eat it too, with Industry 4.0 and IIoT concepts, you can have the best of both of these scenarios. There are many viewpoints of what these terms or ideas mean, but let’s just look at what these two ideas have made available to the market to lessen the burden on our PLCs.

Data Generating Devices Using IO-Link

The technology of IO-Link has created an explosion of data generating devices. The level of diversity of devices, from I/O, analog, temperature, pressure, flow, etc., provides more visibility to a machine than anything we have seen so far. Utilizing these devices on a machine can greatly increase visibility of the processes. Many IO-Link masters communicate over an Ethernet-based protocol, so the availability of the IO-Link device data via JSON, OPC UA, MQTT, UDP, TCP/IP, etc., provides the diagnostics on the Ethernet “wire” where more than just the PLC can access it.

Linux-Based Controllers

After using IO-Link to get the diagnostics on the Ethernet “wire,” we need to use some level of controller to collect it and analyze it. It isn’t unusual to hear that a Raspberry Pi is being used in industrial automation, but Linux-based “sandbox” controllers (with higher temperature, vibration, etc., standards than a Pi) are available today. These controllers can be loaded with Codesys, Python, Node-Red, etc., to provide a programming platform to utilize the diagnostics.

Visualization of Data

With IO-Link devices providing higher level diagnostic data and the Linux-based controllers collecting and analyzing the diagnostic data, how do you visualize it?  We usually see expensive HMIs on the plant floors to display the diagnostic health of a machine, but by utilizing the Linux-based controllers, we now can show the diagnostic data through a simple display. Most often the price is just the display, because some programming platforms have some level of visualization. For example, Node-Red has a dashboard view, which can be easily displayed on a simple monitor. If data is collected in a server, other visualization software, such as Grafana, can be used.

To conclude, let’s not overburden the PLC with diagnostic; lets utilize IIoT and Industry 4.0 philosophy to gain visibility of our industrial automation machines. IO-Link devices can provide the data, Linux-based controllers can collect and analyze the data, and simple displays can be used to visualize the data. By using this concept, we can greatly increase scan times in the PLC, while gaining a higher level of visibility to our machine’s process to gain more uptime.

Adding a higher level of visibility to older automation machines

It’s never too late to add more visibility to an automation machine.

In the past, when it came to IO-Link opportunities, if the PLC on the machine was a SLC 500, a PLC-5, or worse yet, a controller older than I, there wasn’t much to talk about. In most of these cases, the PLC could not handle another network communication card, or the PLC memory was maxed, or it used a older network like DeviceNet, Profibus or ASi that was maxed. Or it was just so worn out that it was already being held together with hope and prayer. But, today we can utilize IIoT and Industry 4.0 concepts to add more visibility to older machines.

IIOT and Industry 4.0 have created a volume of products that can be utilized locally at a machine, rather than the typical image of Big Data. There are three main features we can utilize to add a level of visibility: Devices to generate data, low cost controllers to collect and analyze the data, and visualization of the data.

Data Generating Devices

In today’s world, we have many devices that can generate data outside of direct communication to the PLC.  For example, in an Ethernet/IP environment, we can put intelligent devices directly on the EtherNet/IP network, or we can add devices indirectly by using technologies like IO-Link, which can be more cost effective and provide the same level of data. These devices can add monitoring of temperature, flow, pressure, and positioning data that can reduce downtime and scrap. With these devices connected to an Ethernet-based protocol, data can be extracted from them without the old PLC’s involvement.  Utilizing JSON, OPC UA, MQTT, UDP and TCP/IP, the data can be made available to a secondary controller.

Linux-Based Controllers

An inexpensive Raspberry Pi could be used as the secondary controller, but Linux-based open controllers with industrial specifications for temperature, vibration, etc. are available on the market. These lower cost controllers can then be utilized to collect and analyze the data on the Ethernet protocol. With a Linux based “sandbox” system, many programming software packages could be loaded, i.e. Node-Red, Codesys, Python, etc., to create the needed logic.

Visualization of Data

Now that the data is being produced, collected and analyzed, the next step is to view the information to add the extra layer of visibility to the process of an older machine. Some of the programming software that can be loaded into the Linux-based systems, which have a form a visualization, like a dashboard (Node-Red) or an HMI feel (Codesys). This can be displayed on a low-cost monitor on the floor near the machine.

By utilizing the products used in the “big” concepts of IIOT and Industry 4.0, you can add a layer of diagnostic visualization to older machines, that allows for easier maintenance, reduced scrap, and predictive maintenance.

What data can IO-Link provide?

As an application engineer, one of the most frequent questions I get asked by the customers is “What is IO-Link and what data does it contain?”.

Well, IO-Link is the first worldwide accepted sensor communication protocol to be adopted as an international standard IEC61131-9. It is an open standard, and not proprietary to one manufacturer. It uses bi-directional, single line serial communications to transfer data between the machine controller and sensors/actuators. No other communication protocol is manufacturer and fieldbus independent, and yet provides this level of communication down to the sensor/actuator level. It provides the user with three different data types: process data, parameter data, and diagnostics or event data.

Process Data

Process data of an IO-Link smart device is considered the latest state of that device. Containing both input and output data, process data is cyclically exchanged between IO-Link master and IO-Link slave device (i.e. sensor or actuator). The time interval or data update rate solely depends on amount of data, 1 to 32 bytes, and speed at which an IO-Link slave device communicates. IO-Link standard (IEC61131-9) defines three different communications speeds; COM1 is set to 4.8kBaud (slowest), COM2 is set to 38.4kBaud and COM3 is set to 230.4kBaud (fastest). Depending on the device, process data may contain status of inputs or outputs of remote I/O hub, position feedback of linear transducers, pressure feedback from pressure transducers, information from am RFID (Radio Frequency Identification) reader, and so on. For more information about process data content, refresh rate, and data mapping, one should reference an IO-Link slave device datasheet or user manual.

Lastly, process data is then buffered in memory of the IO-Link master device and passed to the controller via a specific fieldbus at request packet interval. Request packet interval is set in the controller settings.

Process Data

Parameter Data

Parameter data contains information and parameters specific to the IO-Link slave device. This data is exchanged acyclically, which means that it is requested from the IO-Link master or controller and not time based. Parameters can be read from a specific device or written to. Parameter data is primarily used for device configuration, or verification. A key advantage of IO-Link is that it gives the controller the full access to IO-Link slave device parameters, down to a sensor/actuator level. This means that your controller, PLC or PC based, can change the configuration of an IO-Link’s slave device dynamically without taking the device off line, and without use of proprietary cabling or configuration software.

Typical use of parameter data is for automatic machine configuration, recipe change, process tuning, maintenance, and easy component replacement.

Parameter Data

Diagnostics or Event Data

Diagnostic data provides the controller with events that affect the operation and performance of the IO-Link smart device. Content can vary depending on the device used, and the manufacturer. IO-Link smart devices can provide crucial data such as load, temperature, stress level, overload and short circuit diagnostics, error codes, configuration or parameter issues, access issues, etc., as part of diagnostic or event data. The event code size is 2 bytes, and in hexadecimal data format. This information can then be interpreted by the controller/user using a lookup table or IODD (I/O Device Description) file. User manual will have diagnostic data table that can be used as a reference.

Diagnostic and Event Data

Conclusion

In conclusion, IO-Link enables a plug-and-play relationship between the controller and the devices on the machine. Using IO-Link data, the controller can automatically recognize and configure an IO-Link slave device that is connected to its network. Process and diagnostic data provide continuous feedback on machine status and health down to a sensor level — the lowest level of the automation pyramid.

Keep in mind that the content of process data is specific to the device and will vary from device to device, and manufacturer to manufacturer. This makes IO-Link data one of the main differentiators between smart devices and their manufacturers. Luckily, IO-Link is an open standard, and fieldbus and manufacturer independent, so you can mix and match devices best suited for your application without worrying about device compatibility, special cabling, or third-party configuration software packages.

automation pyramid

 

Not All RFID is Created Equal: Is Yours Built for an Industrial Environment?

The retail environments where products are sold look nothing like the industrial environments where they are produced (think of the difference between a new car dealership and an automotive manufacturing plant). Yet the same RFID products developed for retail stores and their supply chain operations are still marketed to manufacturers for production operations. These products may work fine in warehouses, but that does not necessarily qualify them as industrial grade.

IO-Link_RFID

So what are the differences between retail and industrial RFID?

Production environments often require a level of ruggedness, performance, and connectivity that only purpose-built industrial equipment can reliably satisfy. For example, general-purpose RFID equipment may have the physical Ethernet port needed to connect to a PC or server, but will not support EtherNet/IP, Profinet or other industrial protocols that run on PLCs and other industrial automation control equipment. Many retail grade readers need to be supported with an additional protocol conversion, which can require external hardware and slow system performance, and adds to implementation time, difficulty, and expense.

When evaluating RFID equipment, it is essential to make the distinction between what is possible for use in the environment and what is optimal and, therefore, more reliable. There are three fundamental qualities to consider that can determine if RFID systems will perform reliably in demanding production environments:

  • Will the RFID system integrate seamlessly with industrial control systems?
  • Will it provide the reliability and speed that production and their information systems tied in require?
  • Can it maintain uptime and performance long term – will it last on the production line?

RFID is often marketed as a “solution,” however in manufacturing operations, it is almost always used as a supporting technology to provide data and visibility to the MES, ERP, e-Kanban, robotics, asset tracking, material handling, quality control and other systems that run in production facilities. Failure to accurately provide data to these systems at the reliability and speed levels they require eliminates the value of using RFID.

The physical environments in industrial and supply chain settings cause RFID technology to perform differently. Tag density can be a consideration for industrial RFID users like retail, but an industrial environment has much more challenging and powerful potential interference sources, for example, the presence of metal found in most industrial products and environments.

When determining whether RFID products are suitable for a specific environment, it is important to look beyond published marketing hype and misleading specifications. Consider the design and construction of the product and how it could be affected by various work processes. Whenever possible, you should test the products where they will be used rather than in a lab or demonstration area, because the actual work location has interference and environmental conditions that may be overlooked and impossible to duplicate elsewhere.

The key attributes that differentiate industrial RFID equipment from supply chain-oriented alternatives include:

  • Native support for industrial protocols;
  • High tag read reliability and the ability to continuously operate at speeds that won’t slow production systems;
  • Durable housing with secure connectors with IP65 or better rating and relevant certifications for shock, vibration and temperature resistance;
  • The ability to support multiple RFID technologies and supporting devices as needed, including sensors, PLCs, IO-Link, and other industrial automation equipment.

Compromising on any of these criteria will likely result in unnecessary implementation time, support, and replacement costs and increase the risk for system failure.

Increase Efficiencies and Add Value with Data

Industry 4.0 and the Industrial Internet of Things (IIoT) are very popular terms these days.  But they are more than just buzzwords; incorporating these concepts into your facility adds instant value.

Industry 4.0 and IIoT provide you with much needed data. Having information easily available regarding how well your machines are performing allows for process improvements and increased efficiencies. The need for increased efficiency is driving the industry to improve manufacturing processes, reduce downtime, increase productivity and eliminate waste.  Increased efficiency is necessary to stay competitive in today’s manufacturing market.  With technology continuing to advance and be more economical, it is more feasible than ever to implement increased efficiencies in the industry.

Industry 4.0 and IIoT are the technology concepts of smart manufacturing or the smart factory.  IIoT is at the core of this as it provides access to data directly from devices on the factory floor. By implementing a controls architecture with IO-Link and predictive maintenance practices through condition monitoring parameters from the devices on the machine, Industry 4.0 and IIoT is occurring.

Condition monitoring is the process of monitoring the condition of a machine through parameters.  In other words, monitoring a parameter that gives the condition of the machine or a device on the machine such as vibration, temperature, pressure, rate, humidity etc. in order to identify a significant change in condition, which indicates the possible development of a fault.  Condition monitoring is the primary aspect of predictive maintenance.

IO-Link is a point-to-point communication for devices which allows for diagnostics information without interfering with the process data. There are hundreds of IO-Link smart devices, which provide condition monitoring parameters for the health of the device and the health of the machine.  By utilizing capabilities of IO-Link for diagnostics the ability to gather large amounts of data directly from devices on the factory floor gives you more control over the machines efficiency.  Smart factory concepts are available today with IO-Link as the backbone of the smart machine and smart factory.

Dive into big data with confidence knowing you can gather the information you need with the smart factory concepts available today.

The Benefits of Guided Changeover in Packaging

Today’s consumer packaged goods (CPG) market is driving the need for greater agility and flexibility in packaging machinery.  Shorter, more customized runs create more frequent machine changeover.  Consequently, reducing planned and unplanned downtime at changeover is one of the key challenges CPG companies are working to improve.

Many packaging machine builders are now providing fully automated changeover, where motors move pieces into the correct position upon recipe change.  This has proven to be a winning solution, however, not every application can accommodate motors, especially those on older machines.

Guided changeover represents an opportunity to modify or retrofit existing equipment to improve agility and flexibility on older machines that are not yet ready to be replaced.

An affordable intermediate step between fully manual and fully automated changeover: 

A measurement sensor can be added to provide position feedback on parts that require repositioning for changeover.  By using indicator lights, counters or displays at the point of use, the operator is provided with visual guidance to reposition the moving part.  Only once all parts are in the correct position can the machine start up and run.

By utilizing this concept, CPG companies can realize several key benefits:

  • Reduced planned downtime: Adding guidance reduces the amount of time it takes to move parts into the correct position.
  • Reduced unplanned downtime: Providing operator guidance minimizes mistakes, avoiding jams and other problems caused by misalignment.
  • Reduced waste: Operators can “dial in” moving parts quickly and precisely.  This allows the machine to be fully operational sooner, minimizing runoff and scrap.
  • Improved operator training: Providing operator guidance helps CPG companies deal with inevitable workforce attrition.  New operators can be quickly trained on changeover procedures.

Selecting the correct sensor

A variety of sensor technologies can be used to create guide changeover; it’s really a matter of fit, form and function.  Common technologies used in changeover position applications include linear positioning transducers  and encoders.  Other devices like inductive and photoelectric distance sensors can be used with some creativity to solve challenging applications.

Available mounting space and environmental conditions should be taken into consideration when selecting the correct device.  Sensors with enhanced IP ratings are available for harsh environmental conditions and washdown.

Analog devices are commonly used to retrofit machines with older PLCs, while IO-Link can be used in place of analog for a fully digital solution, enabling bi-directional communication between the sensor and controller for condition monitoring, automatic device replacement and parameter changes.

Sensor and Device Connectivity Solutions For Collaborative Robots

Sensors and peripheral devices are a critical part of any robot system, including collaborative applications. A wide variety of sensors and devices are used on and around robots along with actuation and signaling devices. Integrating these and connecting them to the robot control system and network can present challenges due to multiple/long cables, slip rings, many terminations, high costs to connect, inflexible configurations and difficult troubleshooting. But device level protocols, such as IO-Link, provide simpler, cost-effective and “open” ways to connect these sensors to the control system.

Just as the human body requires eyes, ears, skin, nose and tongue to sense the environment around it so that action can be taken, a collaborative robot needs sensors to complete its programmed tasks. We’ve discussed the four modes of collaborative operation in previous blogs, detailing how each mode has special safety/sensing needs, but they have common needs to detect work material, fixtures, gripper position, force, quality and other aspects of the manufacturing process. This is where sensors come in.

Typical collaborative robot sensors include inductive, photoelectric, capacitive, vision, magnetic, safety and other types of sensors. These sensors help the robot detect the position, orientation, type of objects, and it’s own position, and move accurately and safely within its surroundings. Other devices around a robot include valves, RFID readers/writers, indicator lights, actuators, power supplies and more.

The table, below, considers the four collaborative modes and the use of different types of sensors in these modes:

Table 1.JPG

But how can users easily and cost-effectively connect this many sensors and devices to the robot control system? One solution is IO-Link. In the past, robot users would run cables from each sensor to the control system, resulting in long cable runs, wiring difficulties (cutting, stripping, terminating, labeling) and challenges with troubleshooting. IO-Link solves these issues through simple point-to-point wiring using off-the-shelf cables.

Table 2.png

Collaborative (and traditional) robot users face many challenges when connecting sensors and peripheral devices to their control systems. IO-Link addresses many of these issues and can offer significant benefits:

  • Reduced wiring through a single field network connection to hubs
  • Simple connectivity using off-the-shelf cables with plug connectors
  • Compatible will all major industrial Ethernet-based protocols
  • Easy tool change with Inductive Couplers
  • Advanced data/diagnostics
  • Parametarization of field devices
  • Faster/simpler troubleshooting
  • Support for implementation of IIoT/Industry 4.0 solutions

IO-Link: an excellent solution for simple, easy, fast and cost-effective device connection to collaborative robots.

IO-Link reduces waste due to sensor failures

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!

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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.

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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.

You have options when it comes to connecting your sensors

When it comes to connecting I/O in factory automation settings, there are many options one can choose to build an efficient and cost-effective system. This is one area where you can reduce costs while also boosting productivity.

Single Ended Cables and Hardwired I/O

It is common in the industry for single ended cables to be run from sensors to a controller input card in a centralized control cabinet. And while this method works, it can be costly for a number of reasons, including:

  • Flying leads on single ended cables are time consuming to prepare and wire
  • Wiring mistakes are often made leading to more time troubleshooting
  • I/O Cards for PLCs are expensive
  • Long cable runs to a centralized location add up quickly especially when dealing with analog devices which require expensive shielded cables
  • Lack of scalability and diagnostics

Double Ended Cables and Networked I/O

Using double ended cables along with network I/O blocks allows for a cost-effective solution to distribute I/O and increase up time. There are numerous benefits that come along with this sort of architecture. Some of these benefits are:

  • Reduced cabling — since I/O is distributed, only network cables need to be run back to the control cabinet reducing cost and cabinet size, and sensor cables are shortened since I/O blocks are machine mounted
  • Quicker build time since standard wiring is less labor intensive
  • Diagnostics allows for quicker trouble shooting, leading to lower maintenance costs and reduced downtime

IO-Link

Using IO-Link delivers all of the strengths of networked I/O as well as additional benefits:

  • I/O Hubs allow for scalability
  • Smart devices can be incorporated into your system
  • Parameterization capability
  • Increased diagnostics from intelligent devices
  • Reduced costs and downtime
  • Increased productivity

Inductive Coupling for non-contact connection

Many people are using inductive coupling technology to provide a non-contact connection for their devices. This method allows you to pass both power and signal across an air gap making it ideal for replacing slip rings or multi-pin connectors in many applications. This provides some great options for industry to gain benefits in these areas such as:

  • Reduced wear since there is no physical connection
  • Faster change over
  • Reduced downtime due to the elimination of damaged connector pins

For more information on connectivity and I/O architecture solutions please visit www.balluff.com.

Industrial sensors with diagnostic functionality

Self-Awareness
For monitoring functionality in industrial processes two aspects are relevant: Environmental awareness and self-awareness. Environmental awareness analyzes impacts which are provided by the environment (e.g. ambient temperature). Self-awareness collects information about the internal statuses of (sub)systems. The diagnostic monitoring of industrial processes, which are typically dynamic, is  not as critical as the monitoring of static situations. If you have many signal changes of sensors due to the activity of actuators, with each plausible sensor signal change you can be confident that the sensor is still alive and acts properly. A good example of this is rotation speed measurement of a wheel with an inductive sensor having many signal changes per second. If the actuator drove the wheel to turn but the sensor would not provide signal changes at its output, something would be wrong. The machine control would recognize this and would trigger a stop of the machine and inspection of the situation.

Inductive Sensors with self-awareness

DESINA
For level sensing applications in cooling liquid tanks of metalworking applications inductive sensors with self-diagnostics are often used. The inductive sensors detect a metal flag which is mounted to a float with rod fixation.

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Additionally, to the switching output these sensors have a monitor output which is a “high” signal when the sensor status is OK. In situations where the sensor is not OK, for example when there has been a short circuit or sensor coil damage, the monitor output will be a “low” signal.  This type of so called DESINA sensors is standardized according to ISO 23570-1 (Industrial automation systems and integration – Distributed installation in industrial applications – part 1: Sensors and actuators).

Dynamic Sensor control
Another approach is the Dynamic Sensor Control (DSC). Rather than using an additional monitoring output, this type of sensors provides impulses while it is “alive.”

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The sensor output provides information about the position of the target with reference to the sensor as well as status diagnostic of the sensor itself.

IO-Link
With IO-Link communication even teaching of defined switching distance can be realized. The IO-Link concept allows you to distinguish between real-time process data (like target in/out of sensing range) and service data which may be transferred with a lower update rate (in the background of the real process).

For more information, visit www.balluff.com.

This blog post was originally published on the innovating-automation.blog.