Let’s say for a moment you’re considering buying a car. The two top choices are an Alfa Romeo 4C or a minivan. If you’re single, 25 years old, and have lots of money, you might opt for the Alfa. If you’re 35 and have a family with two children, the minivan might win. So how does this concept apply to selecting a wireless protocol?
When dealing with wireless instrumentation, the two main choices are WirelessHART® and ISA100.11a. This has been the case for more than 10 years. Back when those two protocols emerged, there were lots of articles and webcasts discussing why you would pick one over the other. But that was back in 2007. In all likelihood, whichever one you chose would be the only wireless network in the plant. Fast forward to 2019 and the situation is much different. There are all kinds of networks in the plant, wired and wireless. Wi-Fi is everywhere, and in many plants multiple networks are integrated in all sorts of ways people couldn’t imagine in 2007.
So, how do you choose between WirelessHART and ISA100.11a today? That’s the point of Eric Braun’s article in Industrial Ethernet Book, Trade-Offs Selecting a Wireless Instrumentation Protocol.
Given the tens of thousands of wireless instrumentation networks in use globally, there should be no question that these protocols [ISA100.11a and WirelessHART] work as advertised when deployed correctly with a high degree of cyber security. The question as to which protocol to choose is less clear. For purposes of this article, we will focus mainly on the issues of network topology and network management, which are the key differences in the context of how the larger industrial wireless landscape is changing.
Eric makes the point that the two protocols are much alike in many respects, but with critical differences relating primarily to topology and network management. With topology, it’s largely about meshing. ISA100.11a uses a star network which minimizes meshing, while WirelessHART sees meshing as an advantage and employs it extensively.
WirelessHART embraces the meshing concept, using it to create a dynamic self-organizing and self-optimizing network where end devices can communicate directly with the gateway when possible, or via hops from device to device where they are out of range. While meshing can introduce some latency, it is typically a minor consideration and does not affect the overall performance of the network. Network management software constantly monitors network traffic and adjusts meshing patterns automatically as necessary to avoid bottlenecks and transmission delays.
So that brings up network management. ISA100.11a allows administrators to determine how devices and routers talk to each other. Some users may want, or at least they may have considered it important in 2007.
All this was going on a decade or so ago in a context where many process plants were cautiously considering wireless in a variety of ways. Maybe new users were unsure, but it didn′t take long for them to find out that WirelessHART′s self-organizing and self-optimizing capabilities worked extremely well, providing easier implementation as compared to ISA100.11a in many instances.
But things are different now, and the changes should influence choices.
These days, we deal with self-organizing networks everywhere. Nobody has to tell their smartphone to use the best network, whether cellular or Wi-Fi, to complete a call or send a text message. It′s all automatic. At the same time, the range of natively wireless process instruments has grown, plus, whole new classes of wireless condition monitoring sensors (bearing temperature, motor vibration, acoustic transducers, etc.) have exploded onto the market. As these proliferate, the attractiveness of high-performing, self-organizing networks becomes all the more apparent. The easier it is to deploy these devices, the more they will find their way into everyday use where they can deliver improved performance and cost savings.
In other words, don’t put yourself in a situation where you have to manage something that can just as easily manage itself. As for growing integration between industrial networks, a prime example is the new Emerson Wireless 1410S Gateway with the Cisco Catalyst® IW6300 Heavy Duty Series Access Point. This device combines the latest in wireless technology with advanced WirelessHART sensor technology, delivering reliable and highly secure data, even in the harshest industrial environments.
You can find more information like this and meet with other people looking at the same kinds of situations at Emerson Exchange and in the Emerson Exchange 365 community. It’s a place where you can communicate and exchange information with experts and peers in all sorts of industries around the world. Look for the Wireless Groups, and other specialty areas for suggestions and answers.