analog signals Archives - AUTOMATION INSIGHTS

Automation Insights: Top Blogs From 2022

It’s an understatement to say 2022 had its challenges. But looking back at the supply chain disruptions, inflation, and other trials threatening success in many industries, including manufacturing, there were practical insights we can benefit from as we dive into 2023. Below are the most popular blogs from last year’s Automation Insights site.

1. Evolution of Pneumatic Cylinder Sensors

Today’s pneumatic cylinders are compact, reliable, and cost-effective prime movers for automated equipment. They’re used in many industrial applications, such as machinery, material handling, assembly, robotics, and medical. One challenge facing OEMs, integrators, and end users is how to detect reliably whether the cylinder is fully extended, retracted, or positioned somewhere in between before allowing machine movement.

1. Series: Condition Monitoring & Predictive Maintenance

By analyzing which symptoms of failure are likely to appear in the predictive domain for a given piece of equipment, you can determine which failure indicators to prioritize in your own condition monitoring and predictive maintenance discussions.

Read the series, including the following blogs:

1. 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.

1. IO-Link Event Data: How Sensors Tell You How They’re Doing

I have been working with IO-Link for more than 10 years, so I’ve heard lots of questions about how it works. One line of questions I hear from customers is about the operating condition of sensors. “I wish I knew when the IO-Link device loses output power,” or, “I wish my IO-Link photoelectric sensor would let me know when the lens is dirty.” The good news is that it does give you this information by sending Event Data. That’s a type of data that is usually not a focus of users, although it is available in JSON format from the REST API.

1. Converting Analog Signals to Digital for Improved Performance

We live in an analog world, where we experience temperatures, pressures, sounds, colors, etc., in seemingly infinite values. There are infinite temperature values between 70-71 degrees, for example, and an infinite number of pressure values between 50-51 psi.

We appreciate your dedication to Automation Insights in 2022 and look forward to growth and innovation in 2023.

Back to Basics: Analog Signals

Industrial sensors used for continuous position or process measurement commonly provide output signals in the form of either an analog voltage or an analog current. Both are relatively simple interfaces, but there are things to consider when choosing between the two.

Industrial sensors with current output are typically available with output ranges of 0 to 20 mA, which can be converted to 0-10 VDC by using a 500 Ω resistor in parallel at the controller input. Output ranges of 4 to 20 mA, which can be converted to 1-5 VDC by using a 250 Ω resistor in parallel at the controller input. Although it requires a shielded cable, current output allows use of longer cable runs without signal loss as well as more immunity to electrical noise. It is also easily converted to voltage using a simple resistor. Most, but not all, industrial controllers are capable of accepting current signals.

Industrial sensors with voltage output are typically available with output ranges of:

0 to 10 VDC (most common)
-10 to +10 VDC
-5 to +5 VDC
0 to 5 VDC
1 to 5 VDC

One of the main advantages of voltage output is that it is simple to troubleshoot. The interface is very common and compatible with most industrial controllers. Additionally, voltage output is sometimes less expensive compared to current output. With that being said, compared to current signals, voltage signals are more susceptible to interference from electrical noise. To avoid signal loss, cable length must be limited. Voltage output also requires high impedance input and shielded cable.

To learn more about this topic visit our website at www.balluff.us.

Simplify Your Existing Analog Sensor Connection

In my last blog we reviewed how utilizing IO-Link sensors over analog sensors could be cost effective solution as it eliminates need for all the expensive analog I/O cards and shielded cables. In this blog we will see how IO-Link can effectively integrate your analog sensor- in case you want to retrofit your old sensor or maybe just because the IO-Link version for the sensor is not available.

Just to review few main points:

Your beloved analog sensor typically requires a shielded cable run from the sensor to the control cabinet. The shielded sensor cables are usually 1.5x- 2x the cost of the standard M12 prox cables that you probably use elsewhere in the system.
Where to connect the shielded cable? Now, you require analog card (typically 4 channel), which is also expensive compared to digital I/O cards — May be equally expensive as the IO-Link card. But, a 4 channel IO-Link master card could offer lot more compared to the 4-channel analog card. Simply put- your analog card can only take another 3 channels of analog signal where as there are a host of devices that you can connect to the IO-Link master to make your system scalable or future proof – more on this later- I get so excited talking about IO-Link.

In any case, coming back to the point- in general we pay a lot of money to add a single analog sensor in the system. What if we could convert the analog signal to digital (same function that the analog card does), closer to the measurement sensor and get the digital data over a standard prox cable back to the control cabinet or to IO-Link? This way, we can totally eliminate or at least reduce the shielded cable run from sensor to the converter.

Balluff offers this A/D converter module — at Balluff we refer to it as “Hobbit” – it is more like a small adapter that fits directly onto a sensor using the standard M12 fittings. The other side is M12 IO-Link connection to take the data back to the controller via an IO-Link master. This single channel “Hobbit” offers 14 bits of conversion – to ensure you don’t lose data in translation.

If you need more than a single channel, Balluff also offers a 4-channel IO-Link hub, this still utilizes only a single port on the IO-Link master. Now, you have 3 or 7 ports (in case of 8 port IO-Link master), open to connect host of other devices such as digital I/O hubs, valve connectors, SmartLights, RFID, color sensors, Pressure sensors, linear measurement devices and so on…

I hope this blog helps you get little more clarity of many benefits of IO-Link. You can always learn more about the benefits of IO-Link at www.balluff.us/iolink.

On behalf of entire Balluff team, I want to wish you all Happy Holidays and Happy New Year!

5 Tips on Making End-of-Arm Tooling Smarter

Example of a Flexible EOA Tool with 8 sensors connected with an Inductive Coupling System.

Over the years I’ve interviewed many customers regarding End-Of-Arm (EOA) tooling. Most of the improvements revolve around making the EOA tooling smarter. Smarter tools mean more reliability, faster change out and more in-tool error proofing.

#5: Go Analog…in flexible manufacturing environments, discrete information just does not provide an adequate solution. Analog sensors can change set points based on the product currently being manufactured.

#4: Lose the weight…look at the connectors and cables. M8 and M5 connectorized sensors and cables are readily available. Use field installable connectors to help keep cable runs as short as possible. We see too many long cables simply bundled up.

#3: Go Small…use miniature, precision sensors that do not require separate amplifiers. These miniature sensors not only cut down on size but also have increased precision. With these sensors, you’ll know if a part is not completely seated in the gripper.

#2: Monitor those pneumatic cylinders…monitoring air pressure in one way, but as speeds increase and size is reduced, you really need to know cylinder end of travel position. The best technology for EOA tooling is magnetoresistive such as Balluff’s BMF line. Avoid hall-effects and definitely avoid reed switches. Also, consider dual sensor styles such as Balluff’s V-Twin line.

#1: Go with Couplers…with interchangeable tooling, sensors should be connected with a solid-state, inductive coupling system such as Balluff’s Inductive Coupler (BIC). Avoid the use of pin-based connector systems for low power sensors. They create reliability problems over time.

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?”

Analog Signals: 0 to 10V vs. 4 to 20 mA

In the world of linear position sensors, analog reigns supreme. Sure there are all kinds of other sensor interface types available: digital start/stop, synchronous serial interface, various flavors of fieldbus, and so on. But linear position sensors with analog outputs still account for probably two-thirds of all linear position sensors sold.

When choosing an analog-output position sensor, your choice generally comes down to analog voltage (e.g., 0…10 V), or analog current (e.g., 4…20 mA). So which should you choose?

0…10V versus 4…20 mA

When it comes to sensor interface signals, 0…10V is like vanilla ice creamr. It’s nothing fancy, but it gets the job done. It’s common, it’s straightforward, it’s easy to troubleshoot, and nearly every industrial controller on the planet will accept a 0…10V sensor signal. However, there are some downsides. All analog signals are susceptible to electrical interference, and a 0…10V signal is certainly no exception. Devices such as motors, relays, and “noisy” power supplies can induce voltages onto signal lines that can degrade the 0…10V sensor signal. Also, a 0…10V signal is susceptible to voltage drops caused by wire resistance, especially over long cable runs.

A 4…20 mA signal, on the other hand, offers increased immunity to both electrical interference and signal loss over long cable runs. And most newer industrial controllers will accept current signals. As an added bonus, a 4…20 mA signal provides inherent error condition detection since the signal, even at its lowest value, is still active. Even at the extreme low end, or “zero” position, the sensor is still providing a 4 mA signal. If the value ever goes to 0 mA, something is wrong. The same can not be said for a 0…10V sensor. Zero volts could mean zero position, or it could mean that your sensor has ceased to function.

In some cases, 4…20 mA sensors can be slightly more costly compared to 0…10V sensors. But the cost difference is becoming smaller as more sensor types incorporate current-output capability.

For more information on linear position sensors, click here.