PROFINET Communications, Mandatory; Wires, Optional!

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I would like to use PROFINET, but my application is an Automated Guided Vehicle (AGV). It’s battery powered with no preset track.

I would like to use PROFINET, but the machine rotates and slip rings wear out too fast.

If these are your applications, fear not. Since PROFINET uses plain old IEEE 802.3 Ethernet, it can also use IEEE 802.11 WiFi.

Configuring a Wireless Access Point (WAP) for PROFINET is not much more difficult than configuring your home wireless router. But please don’t use a home type WAP in the plant. It will work fine electrically, but its construction is probably not robust enough to survive the atmosphere in your plant. Temperature extremes, high humidity, oily vapor, vibration, and other plant realities are hard on devices built for home use. So choose an industrial WAP. There are many brands to choose from and you can mix and match brands if you have to since they all support the WiFi standard.liseberg_200

Start your wireless PROFINET project by doing (or having done for you) a site survey. That way you will know where to place the WAPs to avoid obstacles and existing wireless signals. WAPS are available with many different types of antennae to suit the situation. My favorite is “leaky coax.” Imagine a coaxial cable not unlike the one that the cable company runs into your house, but a little thicker and with precise slits in the insulation. The wireless signal is thus very much limited to a defined pattern. So you can tightly control where the wireless access is.

There are a number of great leaky coax applications already installed. Have you experienced Disney’s Toy Story Midway Mania? If so, you’ve experienced a leaky coax application. Another favorite is at an amusement park in Sweden where an 80-person glass elevator ascends a 400-foot tall tower. (You can read the details here.)

So go ahead and install IO on a rotating part of the machine while the controller resides on the stationary part. Connect them wirelessly with PROFINET. And your AGV can be a “free range” AGV, not limited to preset routes. Connect it wirelessly with PROFINET.

–Carl Henning

 

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