By Hank Hogan, Contributing Editor

For machines that use presence-detecting proximity sensors, new networking technology offers self-diagnostics, increased flexibility and greater ease of configuration. Other advances have simplified sensor setup, and there is also wireless networking, which provides the advantages of self-healing and fault detection.
However, these capabilities come at a price. More complex and capable proximity sensors carry a premium of perhaps 10-20%.

That seems the case for sensors that support IO-Link (www.io-link.com), an intelligent point-to-point, field-level connection compatible with existing standards. This technology allows the extraction of potentially valuable sensor health information through connection, device and signal data, explains Will Healy III, networking marketing manager for Balluff (www.balluff.com). "You're getting a constant status that the sensor is present, so if something goes wrong with the sensor, you're immediately notified," he says. "Maybe the sensor is working, but the lens is dirty. The next time you do preventative maintenance, you're going to have to clean that off."

Less than 1% of sensors have IO-Link, but Healy predicts it will eventually get to 20%. One reason why is IO-Link allows device settings to be cloned, making it easier to swap out a failed sensor.

This can be done at minimal cost, says Jeff Allison, product manager for photoelectric sensing at Pepperl+Fuchs (www.pepperl-fuchs.us). "You could use IO-Link just to set up the sensor with the sampling rate you want, the response time, the measurement capabilities, the contrast settings or whatever," he explains. "Then unplug it from your computer, and use it in the application without any investment in the application environment."

The company introduced several IO-Link sensors, with more planned for 2012. The cost difference between devices with the new technology and those without will eventually vanish, Allison asserts.

Different situations require different sensing solutions, notes Adam Bainsky, assistant technical marketing manager for sensors at Keyence (www.keyence.com). For instance, tight confines could demand a fiberoptic-based proximity sensor, but a laser-based device might be best for greater gaps. Thus, there probably never will be a one-size-fits-all solution. Even so, Keyence has worked to get closer to universality by introducing its standardized line of neo sensor amplifiers over the past year. "So if you know how to use one, you know how to use all of the series," Bainsky says. "It allows different products to be more universal because they have the same functionality."

Different proximity sensors always will be needed, offers Jeffrey Curtis, senior applications engineer for Banner Engineering (www.bannerengineering.com). For instance, packages on a conveyor in a shipping application might come in many different shapes, sizes, colors and distances. The best solution then might be an ultrasonic sensor, not a light-based one.

But any sensor has to talk to the rest of the plant floor, and here Curtis does see a wide use for wireless. This technology provides an intelligent ability to detect link loss, and could form the basis for a self-healing network. Inclusion of a radio will bump up the price of an individual sensor, but that might be offset by savings elsewhere. "You now have a self-healing network with no hardware installation required," Curtis explains. "And you can monitor that network."

Adam Roycroft, electrical engineering tech at connection maker TE Connectivity (www.te.com), Greensboro, N.C., is aware of IO-Link and other technologies. Most of the sensors on his company's automated production line are of the simple variety, but that could change.

Replacing a sensor or changing over the line to a new product or mix can involve device configuration or adjustments, Roycroft points out. Both can take time, and have to be done correctly. Sensor advances could make such tasks easier, and so the extra expense of a more capable device might be justified. "The reduced downtime when there is a sensor situation—there's a cost associated with that, and it really can pay for itself," he says.

After working as a semiconductor process engineer, Hank Hogan hung up his cleanroom suit and now writes about process control and other technologies from Austin, Texas.