Set up a wireless infrastructure to support a wireless mobile workforce. Here’s advice on industrial environments, challenges include environment, signal integrity, and protocol selection.

Peter Fröhlich

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In setting up wireless infrastructures in industrial environments, challenges include environment, signal integrity, and protocol selection.

Industrial environmental conditions more demanding than in an office environment, with extreme temperatures, dirt, dust, moisture, shock, and vibrations. Industrial grade chipset have improved (passive) cooling and sturdy design to ensure reliability and longevity under these adverse conditions.

High- power electrical consumers, such as engines, welding robots or drives with their frequency converters, cause additional challenges. These can cause overvoltage, glitches, spikes, and noise on power supply lines due to magnetic induction, potential shifts, or high-frequency (HF) coupling. Industrial-grade networking gear uses internal dc-dc coupling with filtering and stabilization that compensates these effects.

Also, the radio can be heavily affected by stray HF noise, various other radios in the environment, and generally highly increased electromagnetic pollution compared to office environments. A special danger in outdoor applications has proven to be a constant threat to office-type access points: lightning strikes in the vicinity, with their extreme currents, cause high voltage spikes in outdoor WiFi antennas, which can easily destroy the radio. New-generation radios designed for industrial use employ overvoltage protection and narrow filters that keep other radio frequencies away and therefore increase reach, reliability, and throughput.

For any new installation only IEEE 802.11n should be chosen as the wireless standard. This standard increases data throughput compared to IEEE 802.11 b or g, although this is often not the prime concern. It also uses spatial information, which means that waves reflected from walls or steel structures are used just as direct waves are for retrieving the data.

Therefore, IEEE 802.11n offers much better stability of the data streams especially in industrial environments where a lot of large structures and metal objects are common.

- Prof. Dr. Peter Fröhlich is director R&D, networking and controls, Hirschmann Automation and Control GmbH, a Belden company. Edited by Mark T. Hoske, content manager, Control Engineering, CFE Media.

www.hirschmann.com 

www.belden.com

ONLINE extra comment from Fröhlich: “At Belden, our Hirschmann, GarrettCom, and Tofino (see diagram below) brands offer a wide range of network switches, routers, firewall and wireless access points and clients for mission critical and industrial applications, all managed by our Industrial HiVision network management tool. Hirschmann began early on to apply WiFi technologies to harsh environments. Over the years we have gathered a lot of experience in various industrial applications. What we have learned about specific challenges in the industrial environment have all gone into a completely new hardware design for our OpenBAT product line.”

Note: Froehlich, traveling at the time of this information request, used a mobile wireless device to compose, edit, and send his advice and comments about industrial infrastructure for mobile wireless devices.

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