Posted on

Know Your RFID Frequency Basics

In 2008, I purchased my first toll road RFID transponder, letting me drive through and pay my toll without stopping at a booth. This was my first real-life exposure to RFID, and it was magical. Back then, all I knew was that RFID stood for “radio frequency identification” and that it exchanged data between a transmitter and receiver using radio waves. That’s enough for a highway driver, but you’ll need more information to use RFID in an industrial automation setting. So here are some basics on what makes up an RFID system and the uses of different radio frequencies.

At a minimum, an RFID system comprises a tag, an antenna, and a processor. Tags, also known as data carriers, can be active or passive. Active tags have a built-in power source, and passive tags are powered by the electromagnetic field emitted by the antenna and are dormant otherwise. Active tags have a much longer range than passive tags. But passive tags are most commonly used in industrial RFID applications due to lower component costs and no maintenance requirements.

Low frequency (LF), high frequency (HF), ultra-high frequency (UHF)

The next big topic is the different frequency ranges used by RFID: low frequency (LF), high frequency (HF), and ultra-high frequency (UHF). What do they mean? LF systems operate at a frequency range of 125…135 kHz, HF systems operate at 13.56 MHz, and UHF systems operate at a frequency range of 840…960 MHz. This tells you that the systems are not compatible with each other and that you must choose the tag, antenna, and processor unit from a single system for it to work properly. This also means that the LF, HF, and UHF systems will not interfere with each other, so you can install different types of RFID systems in a plant without running a risk of interference or crosstalk issues between them or any other radio communications technology.

 

Choosing the correct system frequency?

How do you choose the correct system frequency? The main difference between LF/HF systems and UHF systems is the coupling between the tags and the antenna/processor. LF and HF RFID systems use inductive coupling, where an inductive coil on the antenna head is energized to generate an inductive field. When a tag is present in that inductive field, it will be energized and begin communications back and forth. Using the specifications of the tag and the antenna/processor, it is easy to determine the read/write range or the air gap between the tag and the antenna head.

The downside of using LF/HF RFID technology based on inductive coupling is that the read/write range is relatively short, and it’s dependent on the physical size of the coils in the antenna head and the tag. The bigger the antenna and tag combination, the greater the read/write distance or the air gap between the antenna and the tag. The best LF and HF RFID uses are in close-range part tracking and production control where you need to read/write data to a single tag at a time.

UHF RFID systems use electromagnetic wave coupling to transmit power and data over radio waves between the antenna and the tag. The Federal Communications Commission strictly regulates the power level and frequency range of the radio waves, and there are different frequency range specifications depending on the country or region where the UHF RFID system is being used. In the United States, the frequency is limited to a range between 902 and 928MHz. Europe, China, and Japan have different operating range specifications based on their regulations, so you must select the correct frequency range based on the system’s location.

Using radio waves enables UHF RFID systems to achieve a much greater read/write range than inductive coupling-based RFID systems. UHF RFID read/write distance range varies based on transmission power, environmental interference, and the size of the UHF RFID tag, but can be as large as 6 meters or 20 feet. Environmental interferences such as metal structures or liquids, including human bodies, can deflect or absorb radio waves and significantly impact the performance and reliability of a UHF RFID system. UHF RFID systems are great at detecting multiple tags at greater distances, making them well suited for traceability and intralogistics applications. They are not well suited for single tag detection applications, especially if surrounded by metal structures.

Because of the impact an environment has on UHF signals, it is advisable to conduct a full feasibility study by the vendor of the UHF RFID system before the system solution is purchased to ensure that the system will meet the application requirements. This includes bringing in the equipment needed, such as tags, antennas, processors, and mounting brackets to the point of use to ensure reliable transmission of data between the tag and the antenna and testing the system performance in normal working conditions. Performing a feasibility study reduces the risk of the system not meeting the customer’s expectations or application requirements.

Selecting an industrial RFID system

There are other factors to consider when selecting an industrial RFID system, but this summary is a good place to start:

    • Most industrial RFID applications use passive RFID tags due to their lower component costs and no battery replacement needs.
    • For applications requiring short distance and single tag detection, LF or HF RFID systems are recommended.
    • For applications where long-distance and multi-tag detection is needed, UHF RFID systems are recommended.
    • If you are considering UHF, a feasibility study is highly recommended to ensure that the UHF RFID system will perform as intended and meet your requirements.

Click here to browse our library of Automation Insights blogs related to RFID.

Posted on

Palletized Automation with Inductive Coupling

RFID is an excellent way to track material on a pallet through a warehouse. A data tag is placed on the pallet and is read by a read/write head when it comes in range. Commonly used to identify when the pallet goes through the different stages of its scheduled process, RFID provides an easy way to know where material is throughout a process and learn how long it takes for product to go through each stage. But what if you need I/O on the pallet itself or an interchangeable end-of-arm tool?

Inductive Coupling

1

Inductive coupling delivers reliable transmission of data without contact. It is the same technology used to charge a cell phone wirelessly. There is a base and a remote, and when they are aligned within a certain distance, power and signal can be transferred between them as if it was a standard wire connection.

2

When a robot is changing end-of-arm tooling, inductive couplers can be used to power the end of arm tool without the worry of the maintenance that comes with a physical connection wearing out over time.

For another example of how inductive couplers can be used in a process like this, let’s say your process requires a robot to place parts on a metal product and weld them together. You want I/O on the pallet to tell the robot that the parts are in the right place before it welds them to the product. This requires the sensors to be powered on the pallet while also communicating back to the robot. Inductive couplers are a great solution because by communicating over an air gap, they do not need to be connected and disconnected when the pallet arrives or leaves the station. When the pallet comes into the station, the base and remote align, and all the I/O on the pallet is powered and can communicate to the robot so it can perform the task.

Additionally, Inductive couplers can act as a unique identifier, much like an RFID system. For example,  when a pallet filled with product A comes within range of the robot, the base and remote align telling the robot to perform action A. Conversely, when a pallet loaded with product B comes into range, the robot communicates with the pallet and knows to perform a different task. This allows multiple products to go down the same line without as much changeover, thereby reducing errors and downtime.

Posted on

Inductive Coupling: A Simple Solution for Replacing Slip Rings

1
Figure 1: Inductive coupling for power and data exchange

In the industrial automation space, inductive sensors have grown very popular , most commonly used for detecting the proximity of metal objects such as food cans, or machine parts. Inductive coupling, also known as non-contact connectors, uses magnetic induction to transfer power and data over an air gap.

2.png
Figure 2: Slip ring example

While inductive couplers have many uses, one of the most beneficial is for replacing a traditional slip-ring mechanism. Slip-rings, also known as rotary connectors, are typically used in areas of a machine where one part rotates, and another part of the machine remains stationary, such as a turn table where stations on the indexing table need power and I/O, but the table rotates a full 360°. This set up makes standard cable solutions ineffective.

3
Figure 3: Inductive coupling replacing the slip-ring

A slip ring could be installed at the base of the table, but since they are electromechanical devices, they are subject to wear out. And unfortunately, the signs for wearing are not evident and often it is only a lack of power that alerts workers to an issue.

An inductive coupling solution eliminates all the hassle of the mechanical parts. With non-contact inductive coupling, the base of a coupler could be mounted at the base of the table and the remote end could be mounted on the rotating part of the table.

Additionally, slip rings are susceptible to noise and vibration, but because inductive couplers do not have contact between the base and the remote, they do not have this problem.

Inductive couplers are typically IP67-rated, meaning they are not affected by dirt or water, or  vibrations, and most importantly, they are contact free so no maintenance is necessary.

Learn more about Balluff inductive couplers www.balluff.us.

Posted on

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.

Posted on

Recap of our top 5 posts of 2015

goodbye-2015-hello-2016As we wrap up the old and begin to open up the new, let’s take a moment to reflect on what this past year has brought us.  Apart from the triumphs and the hard lost battles, we want to bring you some of our top posts from 2015.  These posts are as follows:

#5: 5 Tips on Making End-of-Arm Tooling Smarter

Everyone wants their robot to work faster, smarter, and more efficiently.  In this post we review five easy tips to help you improve the efficiency of your end-of-arm tooling.

Example of discrete sensors used to detect tank level
Example of discrete sensors used to detect tank level

#4: Liquid Level Sensing: Detect or Monitor

Who doesn’t like complicated concepts broken down into easy to understand terminology? In this post we break down the differences between point level detection and continuous position sensing as well as provide you with technologies to put into practice.

#3: How Can I Convince My Boss to Send Me to Training?

As Aristotle once said “All men (and women) by nature desire knowledge.”  Here we are giving you the tools needed to break down the barriers your boss (or you) might have against investing in training.

#2: Back to the Basics: How Do I Wire a 2-Wire Sensor?

So you just got a brand spanking new 2-wire sensor for the holidays but you realize you don’t know exactly what wire goes where.  In this post we make wiring that bad boy easy and even break down what polarized and non-polarized mean.

So we have covered four of the top posts from 2015, are you ready for the number one post from the past year? So are we! And we will have it for you right after a quick message from our sponsors! (just kidding!)

power&dataexchange#1: Inductive Coupling – Simple Concept for Complex Automation

Through the use of magnetic induction, we are able to reduce the downtime of a machine due to the failure of a slip ring.  Inductive couplers pass power and data over an air gap creating a maintenance free, non-contact environment to operate a variety of machinery.

We want to thank you for the wonderful year that is behind us and be sure to be on the look-out for even more exciting news to come this year!

Posted on

Non-contact Power & Data Exchange For Assembly Automation

InductiveCouplersAssembly automation has evolved multi-fold since Ford’s first linear assembly plant. Assembly automation is of course commonly found in Automotive or heavy industries but it has found its way in small parts assembly, consumer goods and other industries that are embracing automation full on.

Typically, in assembly automation, pallets of sub-assemblies travel along the conveyor maze making stops at various stations to get further components and assemblies put on or some kind of operation is being performed on them.

Several times, inspection, measurement or other process specifics demand sensors and actuators to be on-board these pallets. A very common challenge people face in this environment is to provide power and communicate with this traveling assembly. Pin based automatic couplers and/ or manual intervention is common solution. As explained in my previous blog “Inductive Coupling for Robotic End Effectors” the pin based coupling has downfall of being susceptible to environmental elements and mechanical wear. Thus, offering a solution that requires some regular maintenance and related downtime. Manual intervention for inspection or measurement is of course time consuming and laborious activity.

Non-contact inductive coupling offers great benefits in this scenario. Typically, the base (transmitter) is mounted along the conveyor and the remote (receiver) is mounted on the moving pallets. As the pallet moves along the assembly line, the remote, when in-zone of the base, receives power and exchanges data over small air-gap with the base unit. There are three major benefits of this approach

  1. Because of magnetic induction phenomenon, these non-contact couplers are immune to dust, humidity, oil or vibrations, unlike the pin based couplers.
  2. Misalignment tolerance: Inductive couplers do not need to be in exact axial or angular alignment. They can tolerate angular or axial offsets. The amount of offset they can tolerate depends on the particulars but typically 10-20° angular offset is acceptable. So over-time when the conveyor system develops some slag, the inductive couplers won’t fail you that easily.
  3. Scalability: Inductive couplers come in various form factors and functionality that includes Power-only, input only, analog, configurable channels of inputs and outputs, and with IO-Link bi-directional communication. IO-Link inductive couplers offer the greatest benefits as they allow exchanging up to 32bytes of data bi-directionally- so in future if the I/O needs grow for your pallets, it can be easily handled.

You can always learn more about inductive couplers on Balluff’s website at www.balluff.us. You can also learn more in our Basics overview.

Posted on

Inductive coupling – simple concept for complex automation

Inductive coupling is not new to automation. The concept in various forms has been around for over few decades. It was not actively used, and my guess is that more than form factor or functionality of couplers, it has to do with automation technology relying on mechanical and hard wired components. With growing complexity and ever evolving technology, the inductive coupling has also evolved.  Nowadays, you can charge your smart phones or tablets using the charging pad that uses the very same technology.

power&dataexchange
Figure 1: Inductive coupling for power and data exchange

In industrial automation space, inductive sensors are very popular and commonly used for detecting proximity of metal objects such as food cans, or machine parts. Inductive coupling uses magnetic induction to transfer power and data over an air gap. Yes, it is a kind of very short range wireless technology that also enables power transfer.

SlipRing
Figure 2: Slip ring example

In this series of blogs on inductive coupling, we can explore various use cases of inductive coupling in complex automation. Today, let’s see how inductive coupling compares with traditional slip-ring mechanism.

Slip-rings, also known as rotary connectors, are typically used in areas of the machine where one part rotates and other part of the machine remains stationary. For example, an indexing table or turn table where stations on the indexing table need power and I/O but the table rotates through full 360°, hence standard cable solutions are ineffective. A slip ring could be installed at the base of the table.

ReplacingSlipRing
Figure 3: Inductive coupling replacing the slip-ring

Since, slip rings are electromechanical devices, in the long term they are subject to wearing out. Unfortunately, the signs of wear are not evident unless one day there is no power to the table. An inductive coupling solution eliminates all the hassle of the mechanical parts. With non-contact inductive coupling, the base coupler could be mounted at the base of the table and the remote coupler could be mounted on the rotating part of the table. Slip rings are susceptible to noise and vibration because they are electromechanical devices, whereas inductive couplers are not because there is no contact between the base and the remote.  In fact, the turn table shown above uses an inductive coupler.

Inductive coupler, typically have IP67 rating for the housing are not affected by dirt or water, are immune to vibrations, and most important they are contact free so no maintenance is required unless you hammer one out. Learn more about Balluff inductive couplers: www.balluff.us.