Wireless Control and Wireless Safety!
Safe wireless (also known as safe cableless) is often applied to a machine using a “zone” concept to reduce the wireless communication distance. As wireless machine communications increase, application questions include the following.
Wireless technology and applications have grown rapidly over the past few years, and safe wireless communication has become part of the discussion. This is particularly important when you look back thirty years or so when communication and control bus technology was driving most of us crazy. We’ve been through the “proprietary” bus stage when suppliers found this approach superior to the “open” bus approach most large end users wanted for their applications. The technology, however, developed quite rapidly and today the distances are greater, communication can be very fast, reliability has increased dramatically, and it’s even applicable for security and safety applications. When compared to wire or cable communication and control wireless technology can be more flexible, less costly to install, and can offer operational savings.
Recently, we’ve seen wireless machine safety applications emerge and the machine safety application standards are re-writing their requirements to address the applications using this technology. In most cases so far it appears that the safe wireless communication is the same as on certified safety bus systems as you hear suppliers promoting their systems. Let’s take a moment and look under the hood.
Safe wireless (also known as safe cableless) is quite often applied to a given machine using a “zone” concept, which dramatically reduces the wireless communication distance. In one of Control Engineering’s recent most read articles, “How to choose wireless technology for industrial applications,” you can read about the importance of distance in wireless applications. It’s my opinion that one reason suppliers use a concept called zone control is to optimize the reliability of communication by creating very short distances between antennas. Yet, at the same time several more (and growing) unrelated wireless devices may also be within the wireless communication zone. These other devices may just be communicating to the general machine control architecture and have nothing to do with machine safety applications. Examples of these machine mounted devices could be temperature sensors, vibration sensors, switches, and pressure sensors…….to mention a few.
A lot of folks in industry, and me included, are wondering how industry applications standards are going to address this multiplicity of simple to complex devices. The complex devices are usually something like a cableless operator panel used for machine set-up, clearing of faults, etc. as in the blog Cableless (Wireless) Operator Panel Applications.
Has anyone come across this emerging issue and can you provide some advice how measures that can be applied to prevent unintended communication problems and possible hazards?
INTEGRATED SAFETY COULD BE YOUR OPPORTUNITY – CONSIDER IT!
As a side note – The 2011 updated NFPA 79, Electrical Standard for Industrial Machinery, was previously expected for release this month. The 2011 NFPA 79 schedule was recently modified and the current expected release date is June, 2011.
Submit your ideas, experiences, and challenges on this subject in the comments section below. Click on the following text if you don't see a comments box, then scroll down: Wireless Control and Wireless Safety!
Contact: www.jbtitus.com for “Solutions for Machine Safety”.
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