The prospect of adding wireless devices to automation architecture is compelling due to the potential business benefits and incremental operational improvements. Another trend that has major implications for the adoption of wireless technology is the Industrial Internet of Things (IIoT).
A key enabler for IIoT connectivity, wireless technology will allow the proliferation of sensors at the device and equipment levels necessary to funnel data to IIoT-connected software applications, systems, and users.
The potential benefits to improve decision support, increase collaboration, reduce costs, and improve business performance provided by the emerging IIoT — combined with today’s increasingly robust and reliable wireless enabling technology — make for a value proposition that is too compelling for industry users to ignore. As such, obstacles such as competing industrial wireless standards at the sensor level have become less daunting.
“We’re seeing signs that industry users have begun to shake off their concerns about wireless technology, opting to harness the operational benefits that wireless affords, rather than sit on the fence,” Allen Avery, senior analyst at ARC, says. “Recent years have brought many examples of success in industrial wireless. In many cases, wireless measurements have reduced implementation costs significantly compared with wired solutions. In other cases, wireless measurements – particularly condition monitoring-related measurements for plant asset management – can now be made that would otherwise be cost-prohibitive or impractical.”
Regulatory woes
There is a growing trend for wireless modules to be added into everyday products beyond the more traditional market of laptops and mobile phones. It is therefore no surprise that the machinery industry is following suit as wireless connectivity becomes the expected norm.
“The increasing use of wireless technologies within machinery has created a situation where manufacturers are unfamiliar with the regulatory requirements, and consequently it is an issue that machinery end-users must also now be aware of,” Neil Dyson, business line manager for machinery safety at global product testing and certification organisation TUV SUD says.
In the European Union (EU) it is mandatory that radio equipment meets the essential requirements of the Radio and Telecommunications Terminal Equipment Directive 1999/5/EC (R&TTE). This will be superseded by the Radio Equipment Directive (RED) (2014/53/EC) in June 2016, but its essential requirements are largely identical to those of the R&TTE Directive, so the situation regarding wireless modules will remain unchanged.
In order to reduce both costs and time to market for new equipment, many machinery manufacturers are relying on the use of wireless modules which already meet some or all of the Directive’s essential requirements, assuming that because the wireless module is compliant as an independent unit, no further action is required. However, this may not be the case.
“While a wireless module can indeed be compliant the Directive, if it is then fully integrated into a machine, which is normally outside the scope of the Directive, then the machine would fall within its scope and the manufacturer would then need to draw up their Declaration of Conformity (DoC) accordingly,” Dyson adds.
The most common method of demonstrating compliance with the Directive’s essential requirements is by using Harmonised Standards. These are written and published under an EU mandate, and provide a presumption of conformity (or compliance), provided they are applied in full. Harmonised Standards are always evolving, so manufacturers must keep abreast of them if they are to continue placing products on the EU market.
Further muddying the already murky waters is the fact that there are different rules that apply to the global marketplace, but there are still some basic guidelines when integrating wireless modules into machines as Dyson explains. “For European compliance, ensure that the wireless module you are integrating is fully compliant with the latest Harmonised Standards and is integrated in accordance with the manufacturer’s supplied instructions. While the module manufacturer should be aware of the integration rules, as a minimum the final or host product manufacturer should check the module’s DoC to ensure that it lists Harmonised Standards which are current.
“It is also important for the host product manufacturer to have access to the module manufacturer’s technical file in case they are asked to prove compliance by a country’s market surveillance authority. This should involve checking the European Union’s Official Journal to see if the standard to which the wireless module was tested has an expiry date and, if so, take action well in advance.
“It is important to remember that products containing wireless transmitters must comply with national radio regulations no matter where in the world they are used. A product containing a wireless transmitter must therefore not be shipped to a non-EU country without checking the regulations.”
Safety first
One area of progression for wireless technology is in safety related control systems. As technology improves, these types of systems will grow in popularity given the benefits of faster response times and a more flexible installed base. While wireless technology affords a great deal of flexibility in terms of how equipment can be deployed across a site, it does have limitations, which is a concern for safety systems where 100 per cent reliability is required.
“One such limitation is the sensing range between receiver and transmitter, the strength of which will depend on the local conditions,” Dyson continues. “The radio signal can be strongly affected by conductive materials, as well as other sources of radio interference, and can sometimes lead to a dead spot for wireless connectivity. This can be caused by metal parts, such as wall armour, insulation and metal foils, which are known to reduce the penetration of radio waves to 0-10 per cent.
“While the RED will become the required method to show compliance of radio and telecoms equipment sold across the EU, equipment compliant with the current R&TTE Directive may continue to be placed on the market until 13th June 2017.”