Guest contributor: Scott Rosenberger, Balluff
Some time ago on Sensortech, we discussed considerations for choosing the right in-cylinder position feedback sensor. In that article, we said:
“…….Analog 0-10 Vdc or 4-20 mA interfaces probably make up 70-80% of all in-cylinder feedback in use…..”
And while that 70-80% analog figure is still not too far off, we’re starting to see those numbers decline, in favor a of newer, more capable interface for linear position feedback: IO-Link. Much has been written, here on Sensortech and elsewhere, about the advantages offered by IO-Link. But until now, those advantages couldn’t necessarily be realized in the world of hydraulic cylinder position feedback. That has all changed with the availability of in-cylinder, rod-style magnetostrictive linear position sensors. Compared to more traditional analog interfaces, IO-Link offers some significant, tangible advantages for absolute position feedback in hydraulic cylinders.
First and foremost, the story of IO-Link is that it offers easy, simple connection of sensors and IO to nearly any industrial network. You can read more about that here.
Another big advantage of IO-Link is the ability to connect sensors to the network using standard, simple, unshielded M12 connectors and cables. Compared to analog systems, which require shielded cabling, and sometimes unusual or proprietary connectors, connecting IO-Link sensors to the network is simpler, and usually less costly.
Unlike their traditional analog counterparts, position sensors with IO-Link offer built-in diagnostic capabilities. Sensor status can be monitored over the network, greatly simplifying troubleshooting and fault detection.
This is where IO-Link position sensors really start to shine. Traditional analog position sensors provide one thing: position feedback in the form of an analog signal (obviously). IO-Link position sensors provide position feedback, of course…but wait, there’s more. In addition to position feedback, IO-Link sensors can provide velocity/speed information, temperature, and differential position (the difference between two position magnets). And the best part? All of this functionality can be freely configured over the network. Plus, sensor configurations can be stored and subsequently downloaded to a replacement sensor if necessary.
It’s worthwhile to point out that IO-Link linear position sensors are ideal for most positioning or position monitoring applications. Just as with analog sensors though, they’re probably not suitable for high-performance closed-loop servohydraulic motion control applications. In those applications, interfaces that are capable of providing super-fast, deterministic data, such Synchronous Serial Interface (SSI) or even Ethernet/IP are more suitable.
You can learn more in this overview flyer.
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