Check before you move from wired to wireless

01Jul

There are cost and operational benefits to be achieved by installing wireless systems for sensor and measurement applications but you have to do your homework first, as Paul Taylor explains

Unfounded worries over the security of wireless systems prevent them ever being seriously considered for installation on site but with the protection afforded by the latest systems, there is really no reason why an organisation should not take advantage of their benefits. Wireless systems can communicate data provided by numerous, widely scattered sensors and measurement instruments back to interfaces on site in a much more user-friendly way than traditional wired systems.

A wireless mesh network is incredibly flexible and resilient. Fundamentally, it works by sending out the signal from one point to a network of receiving points. If one of the receivers fails to pick up the signal, then an alternative point will pick it up and feed it through the network, ensuring a high level of reliability. This is of particular importance to processing operations where critical pressures and levels must constantly be monitored.

But before installing a wireless system, it is imperative that a wireless survey is carried out to identify the available frequency bands. If a neighbouring facility is using a wireless system on the same band, this will result in interference, ultimately rendering the wireless installation ineffective.

It is also important to conduct a comprehensive analysis of the site to ensure that there are no areas where the wireless signal might potentially be severely attenuated. Items like large diameter metal pipes or heavy machinery may obstruct the signal. While wireless mesh networks cope well when a single point fails, the path needs to be relatively clear in the first instance to let the strongest signal through.

One more thing to check before installation is the level of performance required by the site. For instance, if fork-lift trucks are continually driven through the line of the signal, it will need to be strong enough to cope. So, prior to installation, it is essential to determine all the requirements of the wireless system and all possible constraints that might work against it. Ultimately, this will save having to rectify costly mistakes and avoid the need to adapt the system, post-installation. It will also ensure that the system is fit-for-purpose and meets all requirements.

So, the next time you consider investing in a new communications strategy, or upgrading an existing one, don’t ignore the efficiency and productivity benefits offered by a wireless system. The flexibility and resilience of wireless means it can be easily adapted to the changing needs of a site, removing the costs and inconveniences of re-routing cables when new machines are installed and older equipment is removed or re-sited.

Paul Taylor is business manager for industrial communications at Siemens Industry Automation & Drive Technologies