Connecting Safety Devices to a Safety Hub

Safety device users face a dilemma when selecting safety components: They want to create a high-performance system, using best-in-class parts, but this often means buying from multiple suppliers. Connecting these devices to the safety control system to create an integrated system can be complicated and may require different cabling/wiring configurations, communications interfaces and/or long, hardwired cables.

Device-Level Protocols

One solution, discussed in a previous blog on industrial safety protocols, is to connect devices to an open, device-level protocol such as Safety Over IO-Link or AS-i Safety At Work. These protocols offer a simple way to connect devices from various suppliers using non-proprietary technologies. Both Safety Over IO-Link and AS-i Safe offer modules to which many third party devices can be connected.

Connecting to a Safety HubSafety-Arch_012518

The simplest way to connect to a safety hub/module is to buy compatible products from the hub supplier. Many safety block/hub suppliers also offer products such as E-stops, safety light curtains, door switches, inductive safety sensors and guard locking switches which may provide plug & plug solutions. There are, however, also many third party devices which can also be easily connected to some of these hubs. Hubs which are AIDA (Automation Initiative of German Domestic Automobile manufacturers) compliant allow connection of devices which are compatible with this standard. Generally, these devices have M12 connectors with 4, 5 or 8 pins, and the power, signal and ground pins are defined in the AIDA specifications. Most major safety device manufacturers offer at least one variant of their main products lines, which are AIDA pin-compatible.

AIDA/Safety Hub Compatible Devices

Some suppliers have lists of devices which meet the M12 pin/connector AIDA specification and may be connected to AIDA compatible modules. Note that not all the listed safety devices may have been tested with the safety blocks/hubs, but their specifications match the requirements. AIDA compatible devices have been identified from all major safety suppliers including Balluff, Rockwell, Sick, Schmersal, Banner, Euchner and Omron STI; and range from safety light curtains to door switches to E-stop devices.

Easy Connection

While some manufacturers prefer to focus on locking customers into a single supplier solution, many users want to combine devices from multiple suppliers in a best-in-class solution. Selecting a safety I/O block or hub which supports AIDA compatible devices makes it fast and easy to connect a wide range of these devices to create the safety system that is the best solution for your application.

IO-Link — Enables Industry 4.0 and Reduces Costs

Where does IO-Link fit on the road to Industry 4.0 and smart manufacturing?

IO-Link is a major enabling force for Industry 4.0 & smart manufacturing. Motivations for flexible manufacturing, efficient production and visibility require that we have more diagnostics and data available for analysis and monitoring. Lot-size-one flexible manufacturing requires that sensors and field devices be able to adapt to a rapidly changing set of requirements. With the parameterization feature of IO-Link slave devices, we can now send new parameters for production to the sensor on a part by part basis if required. For example, you could change a color sensor’s settings from red to green to orange to grey and back to red if necessary, allowing for significantly more flexible production. With efficient production, IO-Link slaves provide detailed diagnostics and condition monitoring information, allowing for trending of data, prediction of failure modes, and, thus, eliminating most downtime as we can act on the prediction data in a controlled & planned way. Trending of information like the current output of a power supply can give us new insights into changes in the machine over time or provide visibility into why a failure occurred.  For example, if a power supply reported a two amp jump in output three weeks ago, we can now ask, “what changed in our equipment 3 weeks ago that caused that?” This level of visibility can help management make better decisions about equipment health and production requirements.

Has IO-Link been widely accepted? Is anything still holding back its implementation?

In the last year IO-Link has become widely accepted. Major automation players like Balluff, Rockwell Automation, Festo, Siemens, SMC, Turck, Banner, Schmalz, Beckhoff, IFM and more than 100 other companies are engaged, promoting and, most importantly, building an installed base of functional IO-Link applications. We have seen installations in almost every industry segment: automotive OEMs, automotive tier suppliers, food & dairy machinery, primary packaging machinery, secondary packaging machinery, conveying systems, automated welding equipment, robot dress packs, on end-effectors of robots, automated assembly stations, palletized assembly lines, steel mills, wood mills, tire presses and more. The biggest roadblock to IO-Link becoming even further expanded in the market is typically a lack of skillset to support automation in the factory or a wariness of IO-Link as “another industrial network.”

What is the latest trend in IO-Link technology?

One of the biggest trends we are seeing with IO-Link technology is the reduction of analog on the machine.  With analog signals there are many “gotchas” that can ruin a good sensor application: electrical noise on the line, poor grounding design, more wiring, expensive analog input cards, and extra integration work. Analog signals cause a lot of extra math that we don’t need or want to do, for example: a linear position measurement sensor is 205mm long with a 4-20mA output tied into a 16bit input card. How many bits are there per mm?  A controls engineer needs to do a lot of mental gymnastics to integrate this into their machine. With IO-Link and a standard sensor cable, the wiring and grounding issues are typically eliminated and since IO-Link sensors report their measurements in the engineering units of the device, the mathematic gymnastics are also eliminated.  In our example, the 205mm long linear position sensor reports 205mm in the PLC, simple, faster to integrate and usually a much better overall application cost.

Stacklights deliver versatile multi-status indication in real time

With advanced communication technology, stacklights can provide valuable information to operators and floor managers.

Rainer3It’s a new world for real-time, point-of-use information. Stacklights and indicators can provide much more feedback to operators and plant floor managers than ever before.

Using colored lights, stacklights can convey a wide range of information. While red, yellow, green and blue are the standard stacklight colors, a variety of other colors can be used to indicate specific conditions and needs.  It is important to develop a communication plan to clearly identifies what each color and flashing pattern represents.

Figure 1

Color overload can be a problem if not planned out properly. The best planning utilizes a dual color approach where colors are defined by personnel responsible and machine/process status at the point of use. An example would be yellow/blue indication wherein yellow = process slowdown and blue = line supervisor is responsible. This responsibility is clearly on the line supervisor to fix the slowdown at the point of indication. Flashing multiple colors is one method to dual color indication, but that has proven to be confusing. A much more intuitive approach is to segment the indicators based on your communication plan. Even small, point-of-use indicators can be segmented to exceed your goals.

OwnerWe have also seen customers mixing their own colors to achieve a level of differentiation. This differentiation could be simple appearance preference or adherence to their corporate color identity. All very achievable with the new class of smart, LED based stacklights and indicators.

By providing continuously variable information, also referred to as analog information, stacklights can be used to indicate current level status in tanks, hoppers, feeders, flow racks and so on. Continuously variable information is also ideal to use in pacing for operators in manual assembly areas. They can quickly see how much time each individual person has for their process step. If someone is struggling, others can visibly see the situation and step in and help.

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Another popular use is simply displaying that the machine is in idle state, like the spinning icon on computers. This would typically suspend all other forms of indication.  Basically, it indicates the machine is not ready. The color indicators can be used as part of a communication plan to indicate the reason for the idle time and call for specific personnel to respond. As soon as the machine is ready, the indicators and stacklights revert to normal operations, just like your computer.

Stacklights can additionally provide operational status such as flow rates, pressure values and process speed.

To learn more about stacklights and indicators, visit www.balluff.com.

Why IO-Link is the Best Suited Technology for Smart 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.

For more information, visit www.balluff.com/io-link.

Collaborative Automation…It’s Not Just for Robots

Manufacturing is made up of hundreds of discrete operations. Some are repetitive, while others are more diverse. Repetitive tasks are ideal for automation while diverse tasks require more flexibility. And while automation can be extremely flexible, that comes with a high initial investment costs and significant deployment time. The alternative? People!

Humans have the unrivaled ability to adapt to a diverse and flexible manufacturing environment. They can be productive relatively quickly with proper guidance without high initial cost investments.

But as we all know, “to err is human” and this is one of the biggest issues with manual operations. People need a little guidance from time to time. Collaboration is not just for robots; It’s for complete automation systems as well.

Collaborative automation is most important at the point-of-use, where humans are performing critical operations. Some of those common operations include:

  • Manual assembly for low volume or highly flexible operations
  • Delivery of raw materials to the point-of-use
  • Kit assembly for down-stream operation
  • Machine setup and change-over
  • Machine maintenance and calibration

All of these functions can be done error-free and with little training by simply guiding people within their current work envelope, also referred to as their point-of-use. This type of a lean function provides hands-free guidance in the form of indication devices connected directly to your automation system allowing workers to stay focused on the task at hand instead of looking elsewhere for instructions.

With the technology of IO-Link, smart indication devices can now show much more information to all the people involved in specific manufacturing tasks. Automation has an immediate and direct connection to the people that are so vital.

For example, in a manually-fed weld-cell, the smart indicators are capable of not only signaling that the part is loaded correctly, but also whether the part is out of alignment (shown here by the red indicator) or that something wrong with one of the automation components such as a stuck pneumatic clamp.

Figure 1
A manually-fed weld-cell with smart indicators is capable of not only signaling that the part is loaded correctly, but also if the part is out of alignment (shown by the red indicator) or that there is something wrong with one of the automation components such as a stuck pneumatic clamp.

Even better, with IIoT technology, trends can be analyzed to determine if the fixture/tool could be optimized for production or to identify common failure points. This all leads to tighter collaboration with operations, maintenance personnel and production supervisors.

A traditional kitting station, sometimes referred to as a supermarket, is another ideal application for smart indicators. Not only can they guide a single operator to the intended part to pull, they can guide multiple operators at the same time.  Also, smart indicators can inform of incorrect pulls, potential bin options (a physically closure bin), directional information, and inventory levels. And again, with IIoT technology, trends can be analyzed to determine proper layout, individual personnel performance and system throughput. The automation system collaborates with operations, forklift drivers and production supervisors.

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A traditional kitting station, sometimes referred to as a supermarket, with smart indicators to guide operators to the intended part to pull.

So, take a look and see what a collaborative automation system utilizing smart indicators can do for your manual operations. You might be surprised.

Top 5 Insights from 2018

With the start of the new year, let’s take a look at the top 5 insights from 2018.

1. An Easy Way to Remember PNP and NPN Sensor Wiring

“Switched” refers to which side of the controlled load (relay, small indicator, PLC input) is being switched electrically. Either the load is connected to Negative and the Positive is switched (PNP), or the load is connected to Positive and the Negative is switched (NPN). These diagrams illustrate the differences between the two connections…READ MORE

2. Back to the Basics: What is the Value of IO-Link?

With the demands for flexible manufacturing, efficient production & visibility in our factories, smart manufacturing is driving the way we work today.  Analytics and diagnostics are becoming critical to our ability to perform predictive maintenance, improve equipment effectiveness and monitor the condition of the machine as well as the components inside the machine.  Typically, our first reaction is to put these devices onto Ethernet.  However, the implementation of Ethernet requires a high skill set that is scarce in our traditional manufacturers today.  Due to the simple control architecture of IO-Link devices, it allows for many Smart devices to provide the data we need for analytics with a reduction in the Ethernet skill set that has become a roadblock for many manufacturers…READ MORE

3. What Exactly is Safety Over IO-Link?

Users of IO-Link have long been in search of a solution for implementing the demands for functional safety using IO-Link. As a first step, the only possibility was to turn the actuators off using a separate power supply (Port class “B”, Pins 2, 5), which powers down the entire module. Today there is a better answer: Safety hub with IO-Link!…READ MORE

4. Safety Over IO-Link Helps Enable Human-Robot Collaboration

Safety Over IO-Link makes it easier to align a robot’s restricted and safeguarded spaces, simplifies creation of more dynamic safety zones and allows creation of “layers” of sensors around a robot work area.

For the past several years, “collaboration” has been a hot topic in robotics.  The idea is that humans and robots can work closely together, in a safe and productive manner.  Changes in technology and standards have created the environment for this close cooperation. These standards call out four collaborative modes of operation: Power & Force Limiting, Hand Guiding, Safety Rated Monitored Stop, and Speed & Separation Monitoring (these are defined in ISO/TS 15066)…READ MORE

5. DMC vs. RFID in Manufacturing

The increasing discussions and regulations on complete traceability and reliable identification of products is making identification systems an inevitable part in manufacturing. There are two specific technologies that are very well received: The Data Matrix Code (DMC) and Radio Frequency Identification (RFID)…READ MORE

Measuring Distance: Should I Use Light or Sound?

Clear or transparent sensing targets can be a challenge but not an insurmountable one. Applications can detect or measure the amount of clear or transparent film on a roll or the level of a clear or transparent media, either liquid or solid.  The question for these applications becomes, do I use light or sound as a solution?

photoelectric.png
An application that measures the diameter of a roll of clear labels.

In an application that requires the measurement of the diameter of a roll of clear labels, there are a number of factors that need to be considered.  Are the labels and the backing clear?  Will the label transparency and the background transparency change?  Will the labels have printing on them?  All of these possibilities will affect which sensor should be used. Users should also ask how accurate or how much resolution is required.

Faced with this application, using ultrasonic sensors may be a better choice because of their ability to see targets regardless of color, possible printing on the label, transparency and surface texture or sheen.  Some or all of these variables could affect the performance of a photoelectric sensor.

Ultrasonic sensors emit a burst of short high frequency sound waves that propagate in a cone shape towards the target.  When the sound waves strike the target, they are bounced back to the sensor. The sensor then calculates the distance based on the time span from when the sound was emitted until the sound was received.

In some instances, and depending on the resolution required, a time of flight sensor may solve the above application. Time of Flight (TOF) sensors emit a pulsed light toward the target object. The light is then reflected back to the receiver. The elapsed time it takes for the light to return to the receiver is measured, thus determining the distance to the target. In this case, the surface finish and transparency may not be an issue.

Imagine trying to detect a clear piece of plastic going over a roll.  The photoelectric sensor could detect it either in a diffuse mode or with a retroreflective sensor designed for clear glass detection.  But what if the plastic characteristics can change frequently or if the surface flutters.  Again, the ultrasonic sensor may be a better choice and also may not require set up any time the material changes.

So what’s the best solution?  In the end, test the application with the worst case scenario.  A wide variety of sensors are available to solve these difficult applications, including photoelectric or ultrasonic. Both sensors have continuous analog and discrete outs.  For more information visit www.balluff.com.

 

The Need for Data and System Interoperability in Smart Manufacturing

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.IOLink-SmartManufacturing_blog-01To 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.

IOLink-SmartManufacturing_blog-02IO-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.

 

Safely Switch Off Cylinders While Transmitting Field Data

Is it possible to safely switch off cylinders while simultaneously transmitting field data and set up the system in accordance with standards? Yes!

In order to rule out a safety-critical fault between adjacent printed circuit board tracks/contact points (short circuit) according to DIN EN ISO 13849, clearance and creepage distances must be considered. One way to eliminate faults is to provide galvanic isolation by not interconnecting safety-relevant circuits/segments. This means  charge carriers from one segment cannot switch over to the other, and the separation makes it possible to connect the safety world with automation — with IO-Link. Safely switching off actuators and simultaneously collecting sensor signals reliably via IO-Link is possible with just one module. To further benefit from IO-Link and ensure safety at the same time, Balluff’s I/O module is galvanically isolated with a sensor and an actuator segment. The two circuits of the segments are not interconnected, and the actuator segment can be safely switched off without affecting the sensors. Important sensor data can still be monitoring and communicated.

The topological structure and the application of this safety function is shown in this figure as an example:

2D-SAGT-Betriebsanleitung_v2

  1. A PLC is connected to an IO-Link master module via a fieldbus system.
  2. The IO-Link master is the interface to all I/O modules (IO-Link sensor/actuator hubs) or other devices, such as IO-Link sensors. The IO-Link communication takes place via a standardized M12 connector.
  3. Binary switching elements can be connected to the galvanically isolated sensor/actuator hub (BNI IOL-355). The four connection ports on the left correspond to the sensor segment and the four ports on the right correspond to the actuator segment. Communication of the states is done via IO-Link.
  4. The power supply for both segments takes place via a 7/8″ connection, whereby attention must be paid to potential separated routing of the sensor and actuator circuits. Both the power supply unit itself and the wiring to the IO-Link device with the two segments must also ensure external galvanic isolation. This is made possible by separating the lines with a splitter.
  5. An external safety device is required to safely interrupt the supply voltage of the actuator segment (four ports simultaneously). Thus, the module can implement safety functions up to SIL2 according to EN62061/PLd and ISO 13849.  For example, this can happen through the use of a safety relay, whereby the power supply is safely disconnected after actuation of peripheral safety devices (such as emergency stops and door switches). At the same time, the sensor segment remains active and can provide important information from the field devices.

The module can handle up to eight digital inputs and outputs. If the IO-Link connection is interrupted, the outputs assume predefined states that are retained until the IO-Link connection is restored. Once the connection is restored, this unique state of the machine can be used to continue production directly without a reference run.

An application example for the interaction of sensors and actuators in a safety environment is the pneumatic clamping device of a workpiece holder. The position feedback of the cylinders is collected by the sensor segment, while at the same time the actuator segment can be switched off safely via its separately switchable safety circuit. If the sensor side is not required for application-related reasons, galvanically isolated IO-Link modules are also available with only actuator segments (BNI IOL 252/256). An isolated shutdown can protect up to two safety areas separately.

 

Non-Contact Transmission of Power & Data on Transfer Rails & Grippers

For press shops utilizing transfer rail systems, fixed sensor connections regularly cause frustration. Cables and contacts are often subject to heavy strain. Cables can wear out and break, damaged pins or mechanical collisions can cause hours of machine downtime, and the replacement of large multi-pin connectors comes at a high cost.

Inductive couplers offer an ideal solution: By using these non-contact, wear-free products you can eliminate pin connections and simplify job changeovers on the press. Inductive couplers transfer signals and power contact-free over an air gap. The quick-disconnect units are easy to use and require no maintenance, enabling you to meet new demands quickly. Mechanical wear is a thing of the past. This increases system availability, reduces cycle time and enhances the flexibility of workflow processes.

Inductive coupling example

Replace pin connections for transfer rails

Typically, two pin-based connectors connect the transfer rail to the transfer system on the press. The connections are on both the feed and exit sides of the rail to the control. If there is any misalignment of the connections, damage regularly occurs. By replacing the connectors with pin-free inductive couplers, the connections are simplified and repair work is minimized. Additionally you don’t have open pins exposed to the environment (dust, water, oil) that can also cause nuisances in the connection process.

Replace pin connections for grippers

To connect the transfer rail on each gripper, normally a pin-based connector is used. As the grippers are changed on each tooling change, the connectors become worn and damaged with regularity. By replacing the pin connector with non-contact inductive couplers, the two sensor signals are maintained but the maintenance of these connections is reduced dramatically. An additional “in-zone signal” verifies that the gripper is installed and connected. This provides assurance during operation.

Inductive couplers offer IO-Link functionality

Inductive coupling with IO-Link technology adds more benefits besides replacing the pin coupling. It allows users to transfer up to 32 bytes of data in addition to power for actuation or sensors. If you connect IO-Link enabled I/O hubs or valve connectors to the remote side, you can also store identification data on the IO-Link hub or valve. When the connection is established, the controller can request the identification data from the tool to ensure that the system is utilizing the correct tool for the upcoming process.

With pin based coupling you needed up to 4-5 seconds to first engage the tool and to mate the two ends of the pin couplers and then request the identification. With inductive couplers, the base only needs to be brought closer to the remote so that you quickly couple and identify the tool before engaging the tool — this takes less than a second. Additionally the base and remote do not need to be well aligned to couple. Misalignment up to 15-20 degrees of angular offset or 2-4 mm of axial offset still provides functionality.

The benefits at a glance

  • Power and signals transfer with pin-less connectivity
  • Reduced downtime due to rail or gripper repair
  • Know that the gripper is present and powered with in-zone signal
  • Inform the controller that the rail has power and connectivity to the sensors

To decide the right coupler for your next application visit www.balluff.com.