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Photoelectric Basics – Light On or Dark On

Recently I was asked if light on and dark on for a photoelectric sensor was the same as normally open and normally closed.  The short answer is yes, but I think it justifies more of an explanation.  In the world of proximity sensors, capacitive sensors, and mechanical switches when the target is present the output changes state and turns on or turns off; there is no ambiguity.

With photoelectric sensors, instead of normally open or normally closed we refer to light-on operate or dark-on operate because we are referring to the presence or absence of light at the sensor’s receiver.  The output of a light-on operate sensor is on (enabled, high, true) when there is sufficient light on the receiver of the sensor.  Conversely, the output of a dark-on operate sensor is on when the light source is blocked or no light can reach the receiver.

There are three modes of operation with photoelectrics: diffuse, retro-reflective, and through-beam; and the sensing mode determines if the sensor is normally light-on or dark-on.  Retro-reflective and through-beam sensors function as light-on operate sensors because under normal operating conditions there is a reflector or a light emitter providing a light beam back to the sensor receiver.  If no object is blocking the light beam to receiver the output is on, normally closed.  If the target or object is in between the reflector or emitter then the light beam can no longer reach the receiver causing the output to turn off.

Since the diffuse mode of operation requires the target or object to reflect the light source back to the receiver, it functions as a dark-on operate, normally open.  If no object or target is placed in front of the sensor, no light will be reflected back to the receiver.  When the object is present, the output changes state from normally open to closed.

The chart below should help to summarize the above:

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GIZMOS

Plural of Giz-mo.  A noun.  Defined as a gadget, one whose name the speaker does not know.  Customers call us and ask for this or that “gizmo” all the time!  I think we should consider creating a product category simply called “GIZMOS”.

I like to call these things “Enablers” because these devices are very much helping hands that optimize the function of sensors.  A sensor of any brand and manufacturer performs only as well as it’s mounted, matching the fixture to the demands of the application at hand. But how often does this happen in a price-driven world?  They often end up in below-par mounting that fails with regularity, in both pristine environments as well as in hostile environments.  Some examples:

Here’s one example below. These inductive proximity sensors in plastic brackets, showing an exposed coil on one, with corroded mounts on the sensor caused by being beaten to death during parts loading and heat.

gizmo1      gizmo2

With a few “Gizmos” like an application-specific quick change mount, some care in gapping the sensor and guarding the cable/connector system, it could look much different. Check out the examples below.

gizmo4 gizmo5

Photoelectric sensors can suffer the same fate.  In this case, a plastic bodied photoelectric sensor, originally used to replace a fiber optic thru beam pair also suffered abuse. With a little extra beefy mounting, these photoelectric sensors can be expected to last a long time without failure.

gizmo6 gizmo7

There are literally hundreds of these mounting “ENABLERS”, off-the-shelf, cost-effective application specific mounts, guards, actuators and entire systems to help protect your sensor investment.  All categories of products have these “enabling” accessories for Magnetic Field (air cylinder), Inductive Proximity, Capacitive, Ultrasonic, Connectivity, Linear Transducer and Photoelectric product categories.

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Precise Operating Angles

When looking at Ultrasonic Sensor Technology one of the most problematic areas of application is false positive outputs due to a large operating angle. It is not uncommon to have an Ultrasonic Sensor in an application where the sensor has such a large degree of operating angle that the senor is detecting an object other than the desired target. In my past blog post I explained in detail the “Blind Zone” and how important it is to understand your minimum working area. In the video below you’ll see that Ultrasonic Sensors can offer a tight precise “Operating Angle” that detects a desired target without detecting other obstacles that may be present within the application area. For more information on these Ultrasonic Sensors, click here.

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Light it Up! Industrial Stack Lights are old news…

I am seriously excited about the new Smart Light.  It will revolutionize how we automate and interface with people working in the manufacturing environment.  If you didnt watch this video… you need to watch this video.

Even if you don’t know what a stack light is, you will want one of these for your discotec to light it up!

Operating on the open communication protocol IO-Link that I have discussed in previous posts, I think this single part number will improve the factory for:

  • an operator wanting to know when to refill a feederbowl, position a part, or empty a full output bin
  • a maintenance guy needing to know what cell is causing the machine downtime
  • a plant manager wanting to know the machine output, speed, productivity

If you want more information on how this works visit the Smart Light webpage.

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For Industrial Controls, What’s Next After Analog?

Analog signals have been part of industrial control systems for a very long time.  The two most common signals are 0-10V (“voltage”) and 4-20mA (“current”), although there are a wide variety of other voltage and current protocols.  These signals are called “analog” because they vary continuously and have theoretically infinite resolution (although practical resolution is limited by the level of residual electrical noise in the circuit).

Measurement sensors typically provide analog output signals, because these electronic circuits are well-understood and the designs are relatively economical to produce.  But that doesn’t mean it’s easy to design and build a good-quality analog sensor: in fact it is very difficult to engineer an analog signal that is highly linear over its measuring range, has low noise (for high-resolution), is thermally stable, (doesn’t drift as temperature changes), and is repeatable from sample to sample.  It takes a lot of careful engineering, testing, and tweaking to deliver a good analog sensor to the market.

Continue reading “For Industrial Controls, What’s Next After Analog?”

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RFID Marketing: Secrets Revealed

“The world is full of magic things, patiently waiting for our senses to grow sharper.”
-W.B. Yeats

At some point in everyone’s life, they find themself at a proverbial crossroads. They are forced to make a choice that will impact the future. These decisions could create personal fulfillment, affect the people around them, and influence their role in an organization. OK, maybe that’s a little strong for the blogosphere, but what I am trying to say is there is a crossroads where one must differentiate the benefits of a product when the companies that sell them all claim their product is the best and will definitely meet or exceed the needs of their customers.

These days, decision makers not only put their job on the line, but also the future of their company when they pull the trigger on buying new equipment.  And, let’s face it, those wacky marketing people  (I can say that because I am one) haven’t made it any easier to discern one product from another. Let’s use a UHF RFID system, for example.  One could pull spec sheets on 10 different controllers and conclude that “they’re all the same”.  I have heard that exact phrase spoken multiple times from customers who were considering the purchase of a system.  However, we all know that is very far from the truth.

As marketing folk, we have a great challenge in front of us in that we must try to make our product appeal to the whole market in which we are selling. Most of us fell into a monkey-see monkey-do mentality and our spec sheets are filled with speeds and feeds so we can compete with the next guy’s product. So, how is it possible that our customers can make an educated decision when everything appears the same?  We listened to the market, and we wised up.  Instead of just speeds and feeds we added words to help better describe our product. We added words like: “rugged”, “flexible”, “industrial strength”, “turn-key”, .etc.  Now most spec sheets and product descriptions include speeds, feeds, AND fancy buzz words.

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2 Solutions for Preventing Catastrophic Metal Forming Events

Have you ever heard the phrase, “Nine pounds of stuff in a one pound bag?”, or otherwise known as the “Blivet Effect?”

I’ve recently experience this, actually four incidences in three different companies to be exact. It revolves the wrong shut height.  When the recipe in a press doesn’t match die dimensions, or when the die dimensions are estimated, some bad things can happen.

In all of these companies, stamping presses of various tonnage ratings were run with a die that was over shut height dimension (the first hit caused a kaboom!).  Dies were locked up so badly, that they had to be torched, cut, and/or mechanically coaxed out.  In all cases, it took several days for this process to take place, causing lost production and significant down time (not to mention the financial loss and aggravation for a multitude of employees).

In order to eliminate these situations, here are two off-the-shelf electronic solutions that can be installed:
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The Spring Line is Here!

In today’s industrial market, Ethernet cable is in high demand. With words like Ethernet, Ethernet/IP, solid, and stranded, making a decision from the different types of cable can be difficult.

I want to make it easy for you to pick the right cable to go with the network of your choosing.  As a network, Ethernet is easy to install and it is easy to connect to other networks – you can probably even have Ethernet network devices connect to your current network.

So, let’s start with the basics…First, what is the difference between Ethernet and Ethernet/IP?  They both have teal jackets (hence the title – The “Spring Line”) due to the industrial Ethernet standards in North America. So, the difference between the two is in the application.  Ethernet is a good networking cable that transmits data like an internet cable.  Ethernet/IP transmits data and also has an industrial protocol application.  The Industrial Protocol (IP) allows you to transmit more data if you have a lot devices connected to each other or a lot of machines moving at once.  Ethernet/IP resists against UV rays, vibrations, heat, dust, oil, chemical, and other environmental conditions.

Next, there are two kinds of Ethernet IP cables: Solid and Stranded. Solid is great for new applications that require high-speed Ethernet.  The solid cables can transmit and receive across long distances and have a higher data rate compared to stranded.  The downside is that solid cables can break, and do not bend or flex well. Stranded is a better cable if you have to bend, twist, or flex the cable. It’s also better if you have to run short distances.  Stranded is made up of smaller gauge wires stranded together which allows the cable to be flexible and helps protect the cable. They move with the machine and will not break as easily as solid cables.

EthetNetCables_755x220To recap, remember the four short bullet points below when choosing your next cable:

  • Ethernet – transmits data
  • Ethernet/IP – transmits data to many machines/devices
  • Solid – good for long distance and little flexing
  • Stranded– good for short distance and flexing

To learn more visit www.balluff.us

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3 Steps to Choosing the Right In-Cylinder Position Sensor

I recently ran across an interesting article that explored some of the factors involved in selecting hydraulic cylinders.  The article, entitled “3 Steps to Choosing the Right Hydraulic Cylinder” was very informative and helpful.  But what if you need a “smart cylinder”, i.e. a cylinder that can provide absolute position feedback?  Just as it’s important to select the proper cylinder to match the mechanical requirements of your application, it’s also important to select the right sensor to meet the electrical requirements.

So, to that end, I’d like to piggyback on the cylinder selection article with this one, which will look at 3 steps to choosing the right in-cylinder position sensor.  In particular, I’ll be talking about rod-type magnetostrictive linear position sensors that are designed to be installed into industrial hydraulic cylinders to provide absolute position feedback.

Before we get to step 1, let’s talk about the cylinder itself.  So-called smart cylinders are typically prepped by the cylinder manufacturer to accept a magnetostrictive position transducer.  Prepping consists of gun drilling the cylinder rod, machining a port on the endcap, and installing a magnet on the face of the piston.  For more information about smart cylinders, consult with your cylinder supplier.

Step 1 – Choose the Required Stroke Length

The stroke length of the position sensor usually matches the stroke length of the cylinder.  When specifying a position sensor, you usually call out the working electrical stroke.  Although the overall physical length of the sensor is going to be longer than the working electrical stroke, this is usually not a concern because the cylinder manufacturer accounts for this added length when prepping the cylinder.

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The Re-Shoring of American Industry

There’s a quiet revolution underway.  After years of plant closures, outsourcing, and off-shoring, many U.S. companies are re-thinking the way they supply manufactured goods to the domestic market.   The surprising trend that’s emerging? Companies are bringing the production lines and the jobs back to U.S. soil.

The December 2012 issue of The Atlantic magazine contains two very interesting articles detailing the drivers behind this sea change in supply chain strategy.   Take a look at The Insourcing Boom and Mr. China Comes to America.

Automation is going to be a big part of this revived domestic manufacturing effort.  Those who can skillfully deploy sensors and cutting-edge control system architectures – to cost-effectively augment and support a high-productivity U.S. workforce – will find themselves on the winning side of this emerging 21st century economic story.