Why Train on Industrial Ethernet?

trainingAn industrial Ethernet network is vastly different from an office Ethernet network in several key ways, and the key to optimizing your industrial network in light of these differences, is hands-on training.

First of all, the environment in industrial applications can degrade the actual cable itself. Some cable manufacturers actually rate their cables’ ability to withstand these environmental factors. They use the acronym MICE, and rate the cable as appropriate for one of three environments: M1I1C1E1 for office environments, M2I2C2E2 for light industrial environments, and M3I3C3E3 for industrial environments. The letters actually stand for: Mechanical factors such as shock and vibration, Ingress from moisture, Climatic factors such as temperature and sunlight, and Electromagnetic interference such as noise caused by inductive loads, welders, variable frequency drives, etc. Other cable vendors observe the recommendations of ODVA and offer cables that are ODVA compliant.

Secondly, industrial Ethernet networks can have a high amount of multicast traffic. In the early years of Ethernet hubs were used to link devices. The problem is that information coming into one port of a hub was redirected to all of the other ports on the hub. With the advent of switches, unicast traffic was now directed to only the port for the intended recipient device. This is true for both managed and unmanaged switches: they both handle unicast traffic well. The problem for the unmanaged switch comes when you encounter multicast traffic. Since an unmanaged switch does not employ IGMP Snooping (Internet Group Management Protocol), the switch does not know what to do with multicast traffic. It starts acting like the old hubs: it directs all multicast traffic to all ports. With a managed switch and with IGMP Snooping turned on, the switch knows exactly where to send this multicast traffic and directs it only to the intended recipients. Multicast traffic can be anything from produced tags to input modules configured for multicast. These can be very common in industrial applications using PLCs.

Thirdly, we now have tools available in many switches and routers to prioritize the traffic on an Ethernet network. This becomes especially important when you have high-speed applications, motion applications, or time synchronization applications. In the past all Ethernet data was equal. The feedback coming from a servo drive had to wait just as long as a person trying to get online with a PLC. Now many automation vendors are marking their data with priority codes. Allen-Bradley marks their data in layer three with DSCP markings, and Siemens uses layer two markings with PCP marks, for instance (a VLAN tagging mechanism). In either case, if your switch or your routers are not configured properly to recognize and use these priority codes, you are not taking advantage of the QoS feature that could help get your important data through first (Quality of Service).

Only through proper training can you learn not only what the key issues are but also how to properly deploy your hardware to fully optimize your network. Balluff offers hands-on training with actual automation equipment, switches, and routers to help you do just that. You can learn more about the courses Balluff has to offer at www.balluff.us/training.

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If our products could talk, what would they say?

In industrial automation we put our products through a lot. Extreme temperatures, harsh environments, and the demands of high performance can put a strain on the components of any machine. This led me to wonder, if our products could talk, what would they say?

CordsetTalkCordset: Cables have certain limpness which makes installing the cordset in automation easier to fit in tight spaces. Most cable installers prefer to have the least amount of slack in cable to prevent the cable being snagged or pulled during operations. Cables need to have a bend radius to prevent kinking of the conductors and a continuous flow of power. The bend radius is “the smallest radius of curvature into which a material can be bent without damage” (McGraw-Hill Dictionary of Architecture and Construction). Typically in a fixed (stationary) application, an unshielded sensor cable has a minimum bending radius of 8 times the outer diameter of the cable.

PowerSupplyTalkPower Supply: Everyone wants a friend. When a load is too much for one power supply, adding another power supply helps increase the voltage or current output. “The simplest method to create higher current is to connect the power supplies in parallel and leave only one supply in constant voltage mode. Some power supplies are equipped with analog control signals that allow auto-parallel or auto-tracking, a more elegant way to control multiple power supplies. Auto-parallel supplies can be controlled with a single master supply; a second advantage is that all of the master power supplies features can be used.” (Keysight Technologies) By stringing together power supplies, it allows more voltage or current but also keeps operations up and running.

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Absolute Rotary Encoder Sensing Technology: Optical and Magnetic

When it comes to selecting the most appropriate position detection technology for an absolute rotary encoder application, it’s helpful to consider the general advantages and potential disadvantages of the two most common approaches: optical and magnetic.

Optical Encoders

Example of an absolute-coded optical encoder disk

Example of an absolute-coded optical encoder disk

Internally, absolute optical rotary encoders are comprised of:

  1. An LED light source
  2. A rotating coded disk to modulate the light beam from the LED
  3. An array of photodetectors to convert the impulses of light into electrical signals.

The spinning code disk contains a series of concentric tracks that each represent one bit of resolution, and each track is associated with a separate photodetector.

Among optical encoders, there are two main variations: optical mask and optical phased-array. Optical mask encoders are the more straightforward implementation. A grated mask featuring slots of the same size as the slots in the optical disk is placed on top of the photodetectors to prevent the light spilling over from one channel to another. The chief advantage of the optical mask encoder rests in the ability of the encoder manufacturer to offer a variety of resolutions with the same photodetector array simply by changing the optical code disk and associated mask. On the downside, very high-resolution optical mask encoders require a very small air gap between the mask and the disk of about 0.001…0.003″ (25…75μm). Reliably maintaining such a tight gap requires tight manufacturing and assembly tolerances, and can lead to problems in severe shock and vibration environments.

As a result of the limitations of optical mask encoders, phased-array encoders were developed. Rather than relying on only a single detector for each channel, an ASIC (application-specific integrated circuit) provides an array of very small photodetectors for each channel. The responses of these multiple detectors are averaged, producing a more robust detection signal that is less susceptible to variation than a single detector. This additional signal robustness can be used to relax mechanical construction and assembly constraints such as disk flatness, eccentricity, and misalignment. The end result is a wider air gap tolerance for phased-array encoders compared to the optical mask types.

Both optical mask and phased-array detection schemes offer similar application advantages and disadvantages. They are immune to intense magnetic fields found around MRI machines or DC injection braking of AC induction motors. Due to the wider gap between disk and detectors, phased-array encoders are more tolerant of shock and vibration.

Regardless whether optical mask or phased-array detection is employed, both variations are rather susceptible to environmental contamination. Particulates such as dirt, dust, or powders and liquids like water or oil can block or attenuate the optical signals, leading to output errors. Another environmental consideration is that elevated temperatures and temperature variations can accelerate LED aging, leading to reduced light output and less reliable signal detection over time.

Absolute optical encoders are typically available with resolutions ranging from 10-bit (1024 pulses / 360°) to 22-bit (4,194,304 pulses / 360°).

Optical Encoder Disks

There are three popular construction methods for optical disks, each having certain advantages or disadvantages:

  1. Glass + Metal Film
    1. Very flat, allowing for tighter air gap and higher resolution
    2. Fragile; can shatter when exposed to high shock or severe vibration
  2. Metal
    1. More tolerant of high shock and vibration
    2. Higher resolutions not feasible due to weakening of the disk caused by necessarily large number of slots
  3. Mylar
    1. More robust than glass + metal
    2. Susceptible to sag and flutter, requiring a higher air gap that limits resolution

Magnetic Encoders

Example of an absolute-coded magnetic encoder disk

Example of an absolute-coded magnetic encoder disk

Absolute magnetic rotary encoders are comprised of only two components:

  1. An ASIC (application-specific integrated circuit) with integrated precision magnetic sensors
  2. A magnetically-coded rotating disk made of rubber ferrite on a metal carrier substrate

The magnetic disk employs a coding scheme called the Nonius principle, consisting of two concentric, adjacent tracks of alternating north and south magnetic poles. The number of poles on each track differs, typically by one pole. For example, the outer track may have 32 poles and the inner track 31. Going around the disk, there is a continuing shift of pole alignment between the inner and outer track. At any given position around the disk, the offset angle between inner and outer poles is unique.

Example of absolute magnetic encoder internal components

Example of absolute magnetic encoder internal components

Two magnetic field sensors inside the ASIC each produce a sinusoidal signal in response to the north and south poles as they traverse over them. The phase shift between these two signals is unique for every position around the disk. Digital electronics convert this analog phase shift into a serial digital data value corresponding to the absolute rotary position of the disk around 360° of rotation. A great advantage of magnetic encoders is that the maximum gap between the sensing ASIC and the magnetic disk surface is larger than for optical mask encoders. A typical specification for a magnetic encoder gap would be 0.012″ ±0.008″ (0.33mm ±0.2mm), compared to an optical mask encoder requiring a gap of about 0.002″ ±0.001″ (50 μm ±25μm).

Magnetic encoders are extremely robust. Virtually immune to shock and vibration, they are also impervious to many kinds of particulates and liquid contaminants, including non-magnetic (non-ferrous) metal shavings and powders. This ability to tolerate contamination largely reduces or eliminates the need for costly sealed enclosures. The primary caveats when applying a magnetic encoder are the presence of very strong magnetic fields that could disrupt the encoder’s operation and the presence of ferrous particles or dust that would be attracted to the magnetic surface, where they would potentially cause distortion of the magnetic poles.

Although magnetic encoders don’t currently offer the highest levels of resolution available with some optical encoders, they do offer more than enough resolution for a wide range of applications. Absolute magnetic encoders are available with resolutions ranging from 12-bit (4096 pulses / 360°) to 17-bit (131,072 pulses / 360°).

Comparison of Optical and Magnetic Absolute Encoder Operating PrinciplesEncoderTable

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The Pressure to Step Up Performance

PressureSensorAppWe all know the roles of mechanical pressure gauges and switches. They either give us a visual indication of hydraulic pressure, or open or close a switch when reaching a certain threshold pressure. Electronic pressure transducers do the same, but more effectively and with a single component instead of two or three. Furthermore, an electronic pressure transducer provides more output variations, longer life, and greater accuracy.

Mechanical pressure gauges and switches still have their place in fluid power, but with more features and greater accuracy and life, transducers are being specified in a wide variety of applications. In an article recently published in Hydraulics and Pneumatics these applications and their conditions are discussed in greater detail. You can read the entire article on the Hydraulics and Pneumatics website.


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BAH!! How do I detect a weld nut?!?!


2015-07-24 09.04.44

Specialty nut detection sensors failed from mechanical damage or heat from close proximity to welding

In automated manufacturing, part quality issues are a weekly discussion and this continues to be true in most weld shops across North America. One of the more common issues that I encounter in discussions with customers involves nuts being welded to a part.
Nut problems seem to come in a variety of frustrations:

  • upside down
  • no nut present
  • wrong position
  • wrong nut
  • two nuts

There are many different sensing technologies that have been applied or attempted over the years for weld nut detection and each has its pros and cons. In my travels I have personally encountered technologies like machine vision, mechanical plungers, inductive proximity sensors, photoelectric sensors, specially designed “nut sensors” and linear position sensors, to name a few.  The biggest complaints I hear about different technologies is either they are unreliable/unrepeatable or they aren’t rugged enough to survive a hit from big metal parts or they can’t take the heat of close proximity to welding.

Repeatedly we have found two technologies are finding success for tough weld nut detection applications in two different parts of the production process.

  1. Post Process Check Stations – Mechanical Contact with PlungerProx sensor.  This sensor uses a spring loaded pin sized for the proper nut to detect presence, is easily repairable (if necessary) and has the ability to adapt to a wide range of nut threads and diameters.
  2. In-Process Check on Pedestal Welders – weld-nut-detect-btlLinear position feedback on the height of the weld gun can provide exact measurements and feedback on the status of the weld nut from presence to orientation of the nut.

I acknowledge that every nut and every application are different.  I regularly see the key to success is to test and discuss with your local sensor guy about the best technology for the situation.  If you are interested in discussing a particularly difficult application please connect with me on Linked-In or Twitter @WillAutomate.

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Hydraulic Cylinder Position Feedback, Revisited

In a previous Sensortech post entitled “Hydraulic Cylinder Position Feedback“, we discussed the basic concept of hydraulic cylinder position feedback.  In case you might have missed that post, here it is for an encore appearance.

Magnetostrictive linear position transducers are commonly used in conjunction with hydraulic cylinders to provide continuous, absolute position feedback.  Non-contact magnetostrictive technology assures dependable, trouble-free operation.  The brief video below illustrates how magnetostrictive position sensors are used with hydraulic cylinders.

Continue reading

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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/inductive-couplers. You can also learn more in our Basics overview.

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How to Make Plant-based Assets Smarter


traceability…add RFID

Pallets, bins, shipping containers, machine tools, hand tools, calibration equipment, neumatic and hydraulic cylinders, etc, etc, etc can all be given some level of intelligence which would make life easier within the plant. Plant-based assets are truly assets because they make our job easier or they allow us to be more efficient. When workers are efficient they are more productive.

Really it all comes down to the questions that we need answered. Here are a few that I have run into in a plant:
Where are all of my pallets and shipping containers?
How much longer can I use this machine tool before the tolerances are out of range?
Has this gauge been calibrated? when? by whom? what are the parameters?
I need to re-order this part or order spare parts and the manufacturer information has been worn off. What is the serial number, when was this part manufactured, what is the location of this asset within the plant?

Ultimately, if your assets can answer a few questions your life becomes a little less complex. All of the answers are simply written to the RFID tag and when you have a question you can read the information from the tag with an RFID reader, sometimes called an interrogator for obvious reasons. It’s that simple.

For more information on RFID as a solution visit our website at www.balluff.us/rfid

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The Machine Builder’s Guide to Improving Machine Turns

controlpanelEfficiency! Efficiency ! and Efficiency!  Every day, in the industrial environments we are all focused on improving efficiencies in our plants, to be able to do things better, easier, and faster, to get more done with as little efforts as possible. Manufacturers focus their efforts to improve their production processes while machine builders are challenged to produce more machines with limited resources. Sometimes, we focus so much on the human and machine capabilities factors through process improvement initiatives such as six-sigma, KANBAN, and other methods, that we tend to overlook some easier ways that can add tremendous value to our endeavors.

“Machine turns” or “turns” is a powerful measure of productivity for the machine builders to measure their efficiency. This determines, with given resources, how many machines they can produce per year in the same space.

Recently, collecting thoughts from industry experts, reviewing various case studies, and based on personal experiences, we compiled a white paper that reveals on how distributed modular controls architecture can boost productivity in system integration and machine build processes. For over few decades, an automated system is accompanied by a huge controls cabinet hosting processors, power-supplies and terminations of hundreds, if not thousands of wires. Building this cabinet, troubleshooting it and maintaining it is laborious activity that costs money and time all across the life cycle of the system.

Distributed modular controls architecture eliminates lot of these activities, provides tools for ease of troubleshooting and ensures a scalable architecture. Most importantly, it saves valuable labor time per machine. Thus, improving the machine turns on the floor.

Balluff recently released a white paper with practical examples that identifies how machine builders and integrators can significantly impact their operations with the choice of controls architecture. The paper also provides guidance on determining the magnitude of impact you can expect, and offers recommendations on how to go-about making the change.

Request your copy here or visit www.balluff.us for more information.

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How Manufacturing Can Easily Invest in STEM Programs

I continuously hear from manufacturers, machine builders and integrators across our industry that they can’t find qualified people for the job openings they have.  Technicians or Engineers, Controls or Mechanical, all positions are in short supply and heavy demand.

“The Boston Consulting Group (BCG)’s “Made in America” research series estimates the shortage at 80,000 to 100,000 highly skilled manufacturing workers.” SHRM

In addition, according to the same study, the average age in 2013 of these workers was 56 years.  In conference presentations, I have seen segments like Steel or Metalworking show average ages up to 62.  And the demand for Science Technology Engineering & Math (STEM) jobs is only growing.

“Over the past 10 years, STEM jobs grew three times faster than non-STEM jobs, and they are projected to continue to grow by 17% through 2018, compared to 9.8% for all other occupations.” SME – Anna Maria Chávez
CEO, Girl Scouts of the USA


“The United States has one of the lowest shares of college degrees awarded in science and technology.” McKinsey

This collection of data screams to me that we MUST work on encouraging our youth with an interest in manufacturing and automation.  Manufacturers have the opportunity to drive this interest even with small investments that can have a large impact.

Especially important is that we invest in programs for the K-12 level according to McKinsey as relatively few incoming freshmen choose these STEM subjects and less than half complete their degrees.

I am personally passionate about encouraging people of all ages into STEM careers and I love sharing my passion for automation.  We, at Balluff, are investing in technical labs, capstone projects and even middle school after school programs.

If you are interested in how you can get more involved in promoting STEM careers in your community, please reach out to me.

@WillAutomate on Twitter


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