Wireless PROFINET overview


A great advantage of PROFINET over some other competing automation networks is the included support in the specification of wireless technology and most importantly the Industrial features available. This opens up a wide variety of applications which are very difficult or impossible when it comes to normal copper cabling.  Some of these applications might be Automated Guided Vehicles (AGVs), slip rings, a rough environment, shipping and more. Also, wireless is part of the spec, making multi-vendor communication much easier to implement.  In other words, different vendor products can communicate directly with each other, versus having some vendor-specific or proprietary solution required for legacy networks (Ex: PROFIBUS).

Applications

As mentioned, wireless supports many different types of applications or usage scenarios.  There are a variety of reasons you typically would want to use wireless. Maybe because you have to, because it is convenient, or for cost savings on wear and tear.  If you have to, it would probably be due to:

  • Rough environment (cable can’t go at all)
  • Contactless system (monorail)
  • Shipping and ports (ship talks to port remotely)
  • Others

Wireless adds convenient options to reduce wear and tear on moving parts or make it easier to connect as a cable isn’t needed, use of a laptop or tablet/smartphone.  This would be used likely with AGVs, slip rings, outdoors, at airports, in certain factory areas, for mobile diagnostics, operations or control.  Wireless is everywhere now, so PROFINET can support it also for all kinds of applications.

Wireless Technologies

As PROFINET is based on Ethernet technology,  it can work with any Wireless standard from the IEEE 802.11 set or IEEE 802.15.1 set. These include both 2.4Ghz, and 5Ghz Wi-Fi as well as Bluetooth applications.  So, again depending on your application requirements, you have an opportunity to pick the wireless that will work best for your application and a wide variety of vendor solutions are available.  It is also important to point out that standard security mechanisms can also be employed for secure communications.

Wireless Caveats

There are a few wireless caveats we need to mention that we’ll discuss in more detail in our next articles.  This includes the fact that the wireless channel is typically a shared medium which means IO update times will possibly need to be adjusted.  Also,  you’ll need to consider a site survey and possibly other methods to avoid interference or delays.

PROFINET Industrial Wireless Mechanisms

To get around the caveats just mentioned, in addition to the standard Ethernet wireless mechanisms or Bluetooth, many of the PROFINET wireless Industrial vendors also offer some additional ‘industrial’ and rugged features on their wireless units.  So it is better to look for these rather than maybe using an off the shelf unit designed for an office.  Features of these access points and depending on the vendor might include bandwidth reservation, rapid roaming, redundancy, R-coax, antenna diversity and more.  Its recommended to check with the vendors and in PI product guide when looking for your wireless solution and planning your application to get the best in class wireless devices and solutions possible.  It will save you a lot of headaches down the road if you plan ahead and install it correctly the first time with wireless.  Speaking of planning you might want to check out our installation guidelines or attend a class in your area.