5 Steps to Make Troubleshooting Less Troublesome

There’s an old, not so funny joke about troubleshooting electrical devices with a punch line that ends with “is it plugged in?”

The reality is that it is easy to overlook basic or simple issues, especially when troubleshooting mechanical, electrical or software problems isn’t part of your regular routine. But following the basic troubleshooting steps listed below can prevent much frustration and lost time. (To be suggestive, many of these steps can be applied to our everyday lives, not just at work.)

There is a scientific and philosophical rule known more commonly as Occam’s razor that states that entities should not be multiplied unnecessarily. In layman’s terms, the simplest explanation is usually the best one. Occam’s razor is often stated as an injunction not to make more assumptions than you absolutely need to. In other words, do not over complicate things. This is especially important when beginning the troubleshooting process.

Here are five general steps to consider when troubleshooting in manufacturing (and in general):

  1. Identify the problem
    • Take the time to understand the malfunction. Look at the problem from where you believe it starts, not necessarily from the end effect you may be witnessing. Sometimes what you observe is a symptom of the problem but not the problem itself. This is the first critical step and usually dramatically reduces the steps required to diagnose the culprit causing the problem. This may also require checking even the simplest things like whether you have power. (Sorry, couldn’t resist.)
  2. Establish a theory of probable cause
    • This is where Occam’s razor should come in. Start by considering the most obvious things first, whether it be a power supply, a sensor, a cable(s) or even a connector, (especially field attachables). Then work your way to the more complex if needed, from network wiring in networks like Ethernet/IP or Profinet, to network traffic or ladder code sequencing. You shouldn’t start examining the more complex until you have eliminated the most obvious. Sometimes a poor performing sensor cable can mimic code problems. Be sure to make a list so you can easily remember your thoughts and probable causes to prevent covering things twice; that is a huge time waster.
  3. Establish an action plan and execute the plan
    • Start testing probable cause theories to try to determine the actual cause or root cause of the problem. Remember to always consider what you understand as the problem and your theories, then start executing your testing from the simplest possible cause to the more complex (if needed). Be careful not to get distracted by issues you find along the way, like something unrelated you remembered you wanted to take care of but is not related to the current problem. (This is where your written list really comes in handy.) Start examining methodically, don’t jump around and don’t repeat steps you’ve already eliminated.
      Hints: Try swapping components when possible and see if the problem corrects itself. And check that someone didn’t change something recently from the original design. This can many times manifest itself as the proverbial “ghost in the machine” syndrome. Consider this process a ladder you are climbing from the simple lower steps to the higher more complex steps. Using this analogy, why climb higher if you don’t need too.
  4. Verify full system functionality
    • Once you have found what you think may be the problem and corrected it, be sure to validate the system after the repair or replacement and make sure it is functioning as it should. In some rare cases, one root cause can cause other problems or damage, so it is important to ensure the system is functioning as it should before returning it back to service. This may lead to some pushback because of the additional time needed, but it could take the system off-line again even longer if unresolved problems are overlooked.
  5. Document the process.
    • Finally, be sure to document what you found and maybe even how you found it in a log or service documentation system. This is especially important if the problem was caused by a part wearing out from normal wear, as it is likely to happen again. If you can categorize the problem, this will make it easier for you and other staff to detect and remedy if it arises again. You may want to consider reviewing your findings at intervals to see if there are possible improvements or changes, like routine maintenance or more reliable components, that could minimize these problems in the future.

Establishing a good process like this will help you more quickly troubleshoot your application or machine, and even help with home projects. Critical thinking like this helps eliminated wasted time, frustration and most importantly, unplanned down time.

 

Today’s Pressure Sensors: More Options to Meet Your Application Needs

Pressure sensing devices are prevalent in industrial machinery.  

 

There are three types of pressure measurements, each with their advantages and disadvantages. 

Absolute pressure (psia) is referenced to a perfect vacuum. This pressure measurement is always positive and is used in measuring barometric pressure or in altimeters.  

 

Gauge pressure (psig) measurement is measured relative to ambient pressure. Examples of gauge pressure include blood pressure and intake manifold vacuum in an engine. Typically, these types of sensors have an atmospheric vent hole located somewhere in the housing. An advantage to this type of sensor is it can measure both positive and negative, thus it can be used in vacuum applications such as robots picking up glass or other products with suction cups.  

 

Differential pressure (psid) measurement is the difference between two pressure sources. The gauge pressure measurement is really a differential measurement as one side is open to the ambient pressure and the other side is connected to the process pressure. However, for most differential pressure sensors the second pressure source is not the ambient air. 

In the past, pressure sensing was accomplished by mechanical switches that typically used Bourdon tubes, diaphragms or bellows. These devices caused a mechanical movement in the switch as the pressure increased or decreased. A course adjustment screw was used to set the desired set point to actuate the various controls. In addition to the switch, some sort of indication was needed so an analog gauge was also typically required. While these devices solved the control requirement, accuracy was not as reliable as the controls required or what was preferred. 

To convert pressure into an electrical output, several different technologies are used in electronic pressure sensors. The first type of strain gauge technology — Piezoresistive technology — is based on measuring the resistance of a deforming silicon semiconductor. stainless steel housing protects the silicon chip as pressure is indirectly transferred to the membrane with a liquid that is usually silicon oil. This type of measurement is most often used in high dynamic pressures.

Thin film technology utilizes a stainless steel carrier. The resistors and other circuitry are placed on the membrane, and measurement is based on the strain gauge technology. The advantage of the thin stainless steel film is its ability to withstand high peak pressures and burst pressures.  

Thick film technology, which also utilizes strain gauge concepts, uses a ceramic carrier. The resistors and other associated circuitry are placed on a membrane using a thick film process. Ceramic cells offer long-term stability and good corrosion resistance. 

In capacitive measuring cells, one electrode is fitted to an elastic membrane and the other electrode is on the support or housing surface on the opposite side. This forms a capacitor in which one electrode follows the movement of the membrane. As the pressure increases or decreases the distance between the electrodes change causing a change in capacitance. 

 

Today’s pressure sensors incorporate both the switching functions and the display of the current pressure. Since these devices are electronic, there are a multitude of output functions available as opposed to the simple on-off functionality of the mechanical pressure switch. These include multiple discrete PNP or NPN outputs from one sensor with multiple functionalities. In many cases a sensor will provide a single discrete output plus a continuous analog output proportional to the pressure value. The discrete output can provide an alarm function while the analog output provides a dynamic value of the process.

The discrete outputs can be programmed for various operations. First and most important are the set points, sometimes referred to as hysteresis, of when the output should activate (SP) and when the output should reset or turn off (RP). Hysteresis keeps the switching outputs stable even if the system pressure fluctuates around the set point.

In some applications it is desirable to know if the pressure is within operating range for machine functions to continue. The output or outputcan be programmed with a window function. The output will be active as long as the measured values fall between the defined low pressure and the defined upper pressure.

Pressure spikes can cause problems not only with the mechanics of the system but with the logic of electrical controls including outputs changing states quickly or chattering. The electronic sensors offered today include the ability to delay the switching outputs of the sensor. Typically, the delays are programmable up to 50 seconds. 

Pressure is usually measured in PSI or bar with one bar of pressure being equal to 14.5 PSI. When applying pressure sensors various pressures should be taken into consideration. First is the nominal operating pressure of the system. The pressure sensor applied to the system should in the 50 – 60% maximum rating of the sensor as this will provide a safety margin.  

 

Overload pressure can be caused by pressure spikes in the system from valves opening or closing or pump cavitation. These spikes can exceed the specified sensor limit, however, no permanent damage or change will occur. Burst pressure is the pressure that can cause permanent damage to the sensing device or mechanical damage to the sensor.   

 

What if the application involves a paste or thick substance that could potentially clog the orifice or dead space of the sensor? Some pressure sensor manufacturers offer flush mounted pressure sensors. These devices are perfect for detecting pastes, greases or thick substances as the bottom of the sensor has a protective membrane, typically stainless steel.  

 

Today’s display is multifunctional as not only does it display dynamic values but it is also used for programming or configuring the sensor. Included on the display is the pressure, parameters, parameter values, scaling of the device, and output(s) status. Also included are programming keys and, in some cases, keypad lock out functionality. 

The true epitome of a pressure sensor is one that can have all of capabilities I’ve mentioned as well as the ability to provide additional functionality and parameterization. Pressure sensors that connect to networks such as IO-Link can optimize processes allowing process monitoring, configuration and error analysis to take place through the system controller. Digital transmission of analog values ensures high signal quality over longer distances and signal delays and distortions are eliminated.  

 

Networkable sensors, such as IO-Link, reduce downtimes and possible configuration errors with plug-and-play functionality. Maximum system flexibility can be achieved during operation as parameters can be modified quickly and remotely. In addition, process diagnostics, data, and errors are reported directly to the controller and displayed on man-machine interfaces. 

 

Pressure sensors have come a long way from the multiple mechanical based components used in the past in both functionality and capabilities. 

 

Choosing the Right Sensor for Your Welding Application

Automotive structural welding at tier suppliers can destroy thousands of sensors a year in just one factory. Costs from downtime, lost production, overtime, replacement time, and material costs  eat into profitability and add up to a big source of frustration for automated and robotic welders. When talking with customers, they often list inductive proximity sensor failure as a major concern. Thousands and thousands of proxes are being replaced and installations are being repaired every day. It isn’t particularly unusual for a company to lose a sensor on every shirt in a single application. That is three sensors a day  — 21 sensors a week — 1,100 sensors a year failing in a single application! And there could be thousands of sensor installations in an  automotive structural assembly line. When looking at the big picture, it is easy to see how this impacts the bottom line.

When I work with customers to improve this, I start with three parts of a big equation:

  • Sensor Housing
    Are you using the right sensor for your application? Is it the right form factor? Should you be using something with a coating on the housing? Or should you be using one with a coating on the face? Because sensors can fail from weld spatter hitting the sensor, a sensor with a coating designed for welding conditions can greatly extend the sensor life. Or maybe you need loading impact protection, so a steel face sensor may be the best choice. There are more housing styles available now than ever. Look at your conditions and choose accordingly.
  • Bunkering
    Are you using the best mounting type? Is your sensor protected from loading impact? Using a protective block can buffer the sensor from the bumps that can happen during the application.
  • Connectivity
    How is the sensor connected to the control and how does that cable survive? The cable is often the problem but there are high durability cable solutions, including TPE jacketed cables, or sacrificial cables to make replacement easier and faster.

When choosing a sensor, you can’t only focus on whether it can fulfill the task at hand, but whether it can fulfill it in the environment of the application.

For more information, visit Balluff.com

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

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

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

Basics

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

Power

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

Density of IO-Link Devices per IO-Link Master

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

Distance and Speed

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

Non-wireless IO-Link devices

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

Applications

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

Conclusion

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

Factor 1 sensors make auto production more flexible

Have you ever climbed a mountain with a backpack? Then you understand that the lower the load, the less power is needed and the lower the energy consumption. The same is true for cars. And in regard to electric vehicles, this is even more important: The more weight that can be saved somewhere else, the larger the battery can be, thus increasing the range of the electric car.

Lightweight construction is key for weight reduction. By using a sensible mix of materials, weight can be saved without compromising functionality and safety or drastically increasing costs. High-strength steels or light metals are used for body parts or seat frames. However, this mix of materials has an impact on automotive production when it comes to selecting the sensor technology. Inductive sensors have become an indispensable part of automotive construction; however, they react to different metals. This would mean frequent adjustments during production. Fortunately, we have Factor 1 sensors.

Inductive sensors react to metals. Their task is to detect metal objects without contact. The distance at which the corresponding object can be detected by the respective sensor is called the switching distance. The switching distance for standard inductive sensors depends on the material of the metal. Steel, for example, is detected much better than aluminum or copper. The switching distance can be reduced by up to 70% for non-ferromagnetic materials.

 

To eliminate this problem, Factor 1 sensors were developed. They offer all of the advantages of inductive sensors with the added bonus of having the same switching distance for all metals. This makes them ideally suited for the detection of changing objects (steel, aluminum, brass, copper etc.) and a perfect fit for the production of electric cars or anywhere different types of metals need to be used and identified. And because Factor 1 sensors are magnetic-field resistant, they can be used in areas  with strong electromagnetic fields, such as welding plants.

For more information, visit https://www.balluff.com/local/us/products/product-overview/sensors/inductive-sensors/#/inductive-factor-1-sensors

Continuous and Exacting Measurements Deliver New Levels of Quality Control

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

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

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

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

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

Robust Cylinder Feedback Adds Safety to Mobile Equipment Applications

Adding position feedback to a hydraulic cylinder provides several benefits which include increasing the efficiency of a process, automating a function, and adding safety to a machine. Most manufacturers of cylinder sensing products offer both discrete and proportional outputs to achieve the cylinder feedback required of the application. Of the proportional types, there’s been a few technologies utilized through the years which include resistive potentiometers, glass scales, linear Hall effect, optical readers, linear variable displacement transducers (LVDT’s), and magnetostrictive transducers. Of these many technologies, magnetostriction continues to be the technology of choice for many absolute position feedback applications due to its non-contact sensing, repeat accuracies, linearities within a few micrometers, and robust mechanical assemblies.

The phenomenon of magnetostriction was first discovered by James Joule in 1842. Joule found that a ferromagnetic material, such as an iron rod, would change dimensions slightly when subjected to a magnetic field. Today’s magnetostrictive transducers use special ferromagnetic alloys and utilize Joule’s effect as a position marker. Additional electronics, including time-of-flight circuitry, are then used to define the position and/or velocity of the marker. While the technology of the magnetostrictive transducer is sophisticated today, the general principal remains the same and is well proven.

Magnetostrictive transducers are widely used in steel mills, sawmills, tire manufacturers and many other industrial processes. They are also widely used in mobile equipment in industries such as construction, agriculture, and rail maintenance of way vehicles.

One strong application for cylinder feedback in mobile equipment is for operator safety. Large mobile elevated work platforms (MEWPs, aka boom lifts, man lifts, cherry pickers, etc.) do not utilize outriggers to stabilize the machine due to the machine’s ability to drive while the basket (and operator) are at height. These machines are also likely to be rented, leaving the skill of the operator in question. A quality cylinder transducer provides precise position feedback to the electronic control module which determines if the operator is approaching an unsafe working condition. One such scenario is when the boom is at 45 degrees and telescoping further out from the side of the machine. In this case, the joystick controls will limit the operator inputs to keep the machine from extending any further out, keeping the machine within a predetermined working “envelope.” Another popular application would be as a memory function. A good magnetostrictive transducer will allow the operator to “teach” a specific position. The operator can return to the programmed position automatically. Memory functions are useful for repeat actions such as returning a bucket to a specific height. If trucks to be filled are all the same height, the memory function can save time and reduce mishaps, allowing the operator to concentrate on other functions such as turning and driving. In the rail industry, maintenance of way machines uses magnetostrictive transducers to determine the depth of hydraulic tines that are used to compact ballast, or to raise the track to a specific height.

No matter what the application, when reliable feedback of a cylinder is needed, magnetostrictive transducers provide reassuring feedback on mobile machines, even in harsh conditions.

But not all magnetostrictive transducers are found within a cylinder housing. Some manufacturers offer both internal and external products. The arguments for an internal approach center around added protection for the transducer from rocks, dirt, heat, etc., while advocates for an external approach speak of less downtime in the event of a transducer mishap, and the reduced costs and delivery times of using a standard cylinder. A reputable manufacturer with technical experts can help guide your choice.

Whether internal or external, industrial or mobile, the phenomenon of magnetostriction will continue to be the technology chosen for reliable, accurate detection of hydraulic cylinders.

Getting Condition Data From The Shop Floor to Your Software

IIoT (Industrial Internet of Things)  is becoming more mainstream, leading to more vendors implementing innovative monitoring capabilities in the new generation of sensors. These sensors are now multifunctional and provide a host of additional features such as self-monitoring.

With these intelligent sensors, it is possible to set up a system that enables continuous monitoring of the machines and production line. However, the essential requirement to use the provided data for analysis and condition monitoring for preventative and predictive maintenance is to get it from the shop floor to the MES, ERP, or other analysis software suites.

There are a variety of ways this can be done. In this post we will look at a few popular ways and methods to do so.

The most popular and straightforward implementation is using a REST API(also known as RESTful API). This has been the de facto standard in e consumer space to transport data. It allows multiple data formats to be transferred, including multimedia and JSON (Javascript Object Notation)

This has certain disadvantages like actively polling for the data, making it unsuitable for a spotty network, and having high packet loss.

MQTT(Message Queuing Telemetry Transport) eliminates the above problem. It’s very low bandwidth and works excellent on unreliable networks as it works on a publish/subscribe model. This allows the receiver to passively listen for the data from the broker. The broker only notifies when there is a change and can be configured to have a Quality of Service(QoS) to resend data if one of them loses connection. This has been used in the IoT world for a long time has become a standard for data transport, so most of software suits have this feature inbuilt.

The third option is to use OPCUA, which is the standard for M2M communication. OPCUA provides additional functionality over MQTT as it was developed with machine communication in mind. Notably, inbuilt encryption allows for secure and authenticated communication.

In summary, below is a comparison of these protocols.

A more detailed explanation can be found for these standards :

REST API : https://www.redhat.com/en/topics/api/what-is-a-rest-api

MQTT : https://mqtt.org/

OPCUA : https://opcfoundation.org/about/opc-technologies/opc-ua/

Photoelectric Sensors in the Packaging, Food, and Beverage Industry

The PFB industry requires the highest standards of quality and productivity when it comes to both their products and their equipment. In order to keep up with the rising demands to produce high quality parts quickly, many in the industry have incorporated photoelectric sensors into their lines. With their durable designs, accurate measurements and fast data output speeds, it is easy to see why. Combine the sensors’ benefits with the clean and well-lit environment of a PFB plant, and it begins to feel like this product was made specifically for the industry. There are many variants of photoelectric sensors, but the main categories are: through beam, diffuse, and retro-reflective sensors.

Through Beam

Through beam sensors come in many different shapes and sizes but the core idea stays the same. An emitter shoots LED red, red laser, infrared, or LED infrared light across an open area toward a receiver. If the receiver detects the light, the sensor determines nothing is present. If the light is not detected, this means an object has obstructed the light.

Applications:

  • Object detection during production
  • Detecting liquid in transparent bottles
  • Detecting, counting, and packaging tablets

Diffuse Beam

Diffuse beam sensors operate a little differently in that the emitter and receiver are in the same housing, often very closely to one another. With this sensor, the light beam is emitted out, the light bounces off a surface, and the light returns to the receiver. The major takeaway with the diffuse beam sensor is that the object being detected is also being used as the reflecting surface.

Applications:

  • Label detection
  • Monitoring the diameter of film
  • Verifying stack height on pallet

Retro-Reflective Beam

Retro-reflective sensors are similar to diffuse beam sensors in that the emitter and receiver are also contained within the same housing. But this sensor requires an additional component — a reflector. This sensor doesn’t use the object itself to reflect the light but instead uses a specified reflector that polarizes the light, eliminating the potential for false positive readings. Retro-reflective sensors are a strong alternative to through beam when there isn’t room for two separate sensor heads.

Applications:

  • Transparent film detection
  • Detection of shrink-wrapped pallets
  • Detecting any reflective target

RFID Replaces Bar Codes for Efficient Asset Tracking

Bar code technology has been around for many years and is a tried and true means for tracking asset and product movement, but it has its limitations. For example, a bar code reader must have an unobstructed view of the bar code to effectively scan. And the bar code label cannot be damaged, or it is then unreadable by the scanner.

In more recent years, additional RFID technologies have been more readily available for use to accomplish the same task but with fewer limitations. Using RFD, a scanner may be able to read tags that are blocked by other things and not visible to the naked eye. UHF RFID can scan multiple tags at the same time in a single scan, whereas most bar codes need to be scanned individually. This, therefore, increases efficiency and reduces the time required to perform the scans.

Then, of course, there is the human factor. RFID can help eliminate mistakes caused by human error. Most bar code scanning is done with hand scanners held by workers since the scanner has to be in the exact position to see the bar code to get a good scan. While manual/hand-held scanning can be done using RFID, most times a fixed scanner can be used as long as the position of the RFID tag can be guaranteed within certain tolerances. These tolerances are much greater than with a bar code scanner.

With the advent of inexpensive consumable RFID labels, the ease and cost of transitioning to RFID technology has become more feasible for manufacturers and end users. These labels can be purchased for pennies each in rolls of several thousand at a time.

It should be noted that several companies now produce printers that can actually code the information on a RFID label tag while also printing data, including bar codes, on these label tags so you have the best of both worlds. Tags can be scanned automatically and data that can be read by the human eye as well as a bar code scanner.

Some companies have expressed concern about the usage of RFID in different countries due to local regulations regarding the frequencies of radio waves causing interferences.

This is not an issue for HF  and UHF technology. HF is an ISO standard (ISO 15693) technology so it applies to most everywhere. For UHF, which is more likely to be used due to the ability to scan at a distance and scan multiple tags at the same time, the only caveat is that different areas of the world allow scanners to only operate in certain frequencies. This is overcome by the fact that almost all UHF tags that I have encountered are what are called global tags.

This means these tags can be used in any of the global frequency ranges of UHF signals. For example, in the North America, the FCC restricts the frequency range for UHF RFID scanners to 902-928 MHz, whereas MIC in Japan restricts them to 952-954 MHz, ETSI EN 300-220 in Europe restricts them to 865-868 MHz, and DOT in India restricts them to 865-867 MHz. These global tags can be used in any of these ranges as they work from 860 to 960 MHz.

On the subject of UHF, it should be mentioned that in addition to the frequency ranges restricted by various part of the world, maximum antenna power is also locally restricted.

For more information on RFID for asset tracking, visit https://www.balluff.com/local/us/products/product-overview/rfid/