From the president's desk

SAIMC

IBG - SA Instrumentation & Control Buyers' Guide

November 2006 SAIMC

Signal transmission in measurement and control probably started with a lever, a simple mechanical device that transmits and amplifies movement from one end of a rod to the other. Then came flexible cables, stepper motors, pneumatics, voltage modulation, current modulation, and now we have electronic bus systems.

As these technologies evolved, manufacturers attempted to force the cross selling of their products by using a unique communication technique. Consumer demand and the need to break into new markets eventually forced the manufacturers to adopt an 'open' transmission method. An example was the 4 to 20 mA standard.

Vivian MacFadyen

Recently, there has been a plethora of bus systems developed with their supporters fervently supporting them. National pride is one reason for this, but the major reason is money. The development costs are astronomical, and it is therefore necessary to employ financial and personnel resources to maintain the interest in these products. Fan clubs have developed worldwide to support these technologies that results in further cost.

Surely it is time to widen out and look at what we are doing, and see the big picture. All we need to do is measure and control, it is as simple as that, and the mode of signal transmission could be transparent. Imagine if the cost of developing and marketing exclusive transmission systems was employed in improving sensors, receivers and community upliftment projects.

Now we have a new opportunity. The glory days of hard-wired bus systems are winding down, soon to be replaced by wireless methods. This is an exciting opportunity opening the way for mesh networks allowing all transmitters to communicate with each other and with all control systems within the facility. This will not necessarily be a saving in the cost of cable, but just imagine the fantastic opportunities to enhance controllability and safety.

Already, there are more systems than one might imagine. The industrial wireless technology with possibly the greatest potential is ZigBee. This short-range wireless technology was a premeditated design specifically for industrial applications. Over 80 companies have come together in the ZigBee Alliance to promote and support this technology. These companies are listed on the website www.zigbee.com, and the Electronic Design website www.elecdesign.com/Articles/Index.cfm?ArticleID=8763&pg=1 makes some interesting reading.

I am not particularly endorsing ZigBee, but my plea is to instrumentation manufacturers to work now toward a common standard of signal transmission. This will open the way for better measurement techniques, control and safety. This opportunity should not be missed.

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