This article is part of the Wireless Wish List series on industrial wireless networks. View the rest of the series here.
Yet another irony about wireless is that it's growing acceptance and widespread deployment in recent years is creating so many applications in so many places that users, system integrators and suppliers often aren't sure what's running or going in where, which can obviously trigger annoying and severe problems that could derail what it's achieved so far and hinder future gains.
"Most users adopt wireless based on standards like Bluetooth (IEEE 802.15.4), Wi-Fi (IEEE 802.11), ISA 100 (ANSI/ISA100.11a and IEC 62734) and WirelessHART (IEEE 802.15.4 and IEC 62591). Many vendors are adding these and other types of wireless to process skids and other equipment, or they're using it to get more data to their PLCs or DCS," says Scott McNeil, industrial network and security architect at Global Process Automation (GPA), a system integrator in Wilmington, N.C., and member of the Control System Integrators Association (CSIA). McNeil also produces the Industrial Wi-Fi Shop blog. "However, local users may have no idea when a contractor adds Wi-Fi or a cellular uplink to monitor their onsite equipment if the installer doesn't tell anyone. Consequently, when the user goes to add their own wireless devices, such as Internet of Things (IIoT) sensor, they suddenly run into interference, data collisions and other communications problems."
McNeil reports these conflicts are why it's still crucial for users to conduct a site and risk assessment before implementing a wireless network and components. "You've got to own your airspace, and know what's going on in it," explains McNeil. "Luckily, there are many free scanner tools available for examining wireless networks and sites that users can run on their laptops, tablet PCs and smartphones. Even if a device like a variable-speed drive (VSD) doesn't have Wi-Fi, it still could possibly be emitting some radio frequency (RF) noise, so users can run a spectrum analysis with MetaGeek's Chanalyzer software."
Assessing all activity
McNeil reports the wireless assessment process begins with a passive survey that continuously samples all of a process or facility's onsite, wireless environment, and develops a "heat map" of all the wireless activity in that location. For example, he adds that NetAlly's Air Magnet software provides wireless monitoring, auditing, troubleshooting and analysis of Wi-Fi networks. Next, a spectrum analysis identifies equipment that's creating electromagnetic interference (EMI) in the radio frequencies used by Wi-Fi or other wireless protocols.
"For instance, 2.4 GHz Wi-Fi only has three non-overlapping channels, which limits real-world usability, but 5 GHz Wi-Fi has more channel space with 24 non-overlapping channels. Of course, 5 GHz and 6 GHz Wi-Fi run at higher frequency, which can give them more range with the right antenna, but reduces their ability to penetrate objects and obstacles," explains McNeil. "This is all about finding the best-fit technology for what users wants to accomplish, and then informing their providers about their goals."
After the initial assessment is done, site owners and their partners can combine its results with the project's goals to design a predictive wireless solution with the best chance of reliably serving its user. McNeil adds that good designs are based on the site's physical characteristics and activities, what speed/bandwidth and data throughput its process requires, and other factors.
"If we're dealing with a large site, such as a warehouse that happens to run a warehouse management system, then we'll likely need to know its existing latency tolerance, the bandwidth of the communications and software we want to add, and whether the user needs to operate in real-time or near real-time," says McNeil. "If we're working with a tank farm that wants to add wireless sensor, we need to be clear about how much data the user needs and how often they need it. Do they need constant updates, or is it OK to get them every five to 10 minutes? Will there be power at the mounting locations, or will the devices need to be battery-powered? Will there be an Ethernet handoff, or will remote I/O need to tie directly to the sensor? Without all this background information going back to the system integrator and supplier, we'll will end up with a costly solution that doesn't give the user the performance and results they expected."
Test and seek validation
Once the right wireless solution is up and running, McNeil stresses it still needs a validation survey and end-device testing, including a second passive survey to make sure it's delivering the coverage that was planned. "We test for everyday issues, but also try to break the system and identify unusual situations," says McNeil. "Through all these phases from design to validation testing, documentation is key because it gives us a reference that lets us check back on designs and performance issues, and answer questions. This is especially important when a third-party is brought in to do troubleshooting or validation, which is a best practice for avoiding bias. Validation testing also helps when plant-floors change and need to be reevaluated to see where more Wi-Fi may be needed."
For example, McNeil reports he recently conducted a wireless assessment for a paper mill and its heavy equipment. This project included the Italian manufacturer offering the option of providing Google Glass headsets; meeting online with the mill's personnel, instead of spending $200,000 on travel; and using augmented reality to virtually show the users how to calibrate and check their equipment. "This virtual option only cost $30,000, and could be done in real-time with sufficient bandwidth," says McNeil. "My assessment found they had what they needed in two of three places, but the location had performance issues due to 2.4 GHz interference from a VSD. So, we had to make sure the wireless access point was only broadcasting in the 5 GHz spectrum and that the Google headsets were 5 GHz capable, which they were. This let them avoid the interference, work flawlessly, save lots of money, and keep their users happy."
