Communications & Networks
Brave new world: Your guide to making the right wireless decisions in your plant
June 12, 2009 by Jeff Becker
Wireless networks have become an essential part of communication in the last century. From the Internet to cell phones, this invisible technology has grown in popularity since the first radio broadcast and has since become one of the world’s favorite buzz words.
While consumers and commercial users tend to take immediate advantage of wireless technologies as they become available, industrial users have historically been a bit more cautious. This caution is generally due to concerns related to critical infrastructure security and reliability. However, if they choose the right wireless solution, early adaptors of industrial wireless technology can have the best of both worlds – security and reliability while leveraging the efficiency and benefits of wireless technology.
The decision to implement wireless technology in an industrial facility is a strategic choice. So how can industrial plants truly begin to make sense of this new wireless world and choose which wireless solution (if any) is the right one? The answer can be found by asking the right questions.
Question #1: Should I choose a single versus multi-purpose network? While single-purpose networks may appear to be the most cost-effective approach for your first deployment, this is rarely the case. Very few plants ultimately use wireless technology for only a single task. A multi-purpose network that handles multiple functions is typically about the same initial price and will yield greater efficiency and be a more effective solution for the long-term.
Are you willing to consider simple control applications? Many operators might want to consider open-loop control for non-critical assets in the future. It is far easier to take a wireless system capable of doing simple control and use it for monitoring and alerting than the opposite, taking a monitoring network and trying to use it for control. This encourages future flexibility of the system.
Do you want field workers with wireless handheld devices to be able to access data and interact with servers in the facility? Because field workers and first responders typically communicate via Wi-Fi networks, the industrial wireless network could jam during a plant emergency if it is not Wi-Fi compatible. Therefore, if you plan to enable field workers at some point in the future, it would be a good idea to select a compatible network when making the initial wireless investment.
Question #2: Do I need multi-speed support? Do you need information to reach the control room quickly for some applications and less quickly for others? Can you afford to have your alarms transmitted back at the same rate as monitoring information? Some measurements require fast responses while others can endure a slower update rate. For example, if a network only supports a fast speed, the slower applications can unnecessarily consume battery life and bandwidth. On the other hand, slower-speed networks may not provide sufficient reporting for more critical applications. In general, you should ensure your network can support multiple reporting needs.
Question #3: How reliable is my network? Is it important that the data is available within the scheduled update time, or is data timeliness not important? Different applications have different requirements. To ensure future flexibility, look for a system that not only has industrial-grade uptime, but one that does so with predictable, sub-second latency. Also, make sure the system can recover from RF path failure or hardware failures.
Question #4: What type of security do I need? Security is essential to protect against malicious intent and to safeguard your people, intellectual property and your bottom line. Security should be simple to deploy, easy to maintain and offer multiple layers of protection.
What type of security do you need? Consider the location of the plant, any potential harm that could come from a security breach and the criticality of the data. For systems that require high security, a system should offer strong encryption, robust authentication and layered protection from attack. It is important that the system offer end-to-end security, meaning that data is not decrypted until it reaches the wired network. Quiz your vendors and implementation team about how security is integrated into the system design and architecture. Security is only as good as its implementation, so make sure that the system you purchase has been tested and validated by credible third-party organizations.
Question #5: Do I need self-contained and predictable power management? When most users consider wireless deployments, they focus on the cost advantage and the absence of wiring, but they also envision the downside of changing batteries in devices throughout the entire facility.
How long do you want your wireless devices to be self-powered? The maintenance expense of swapping batteries should not negate the cost savings of less wiring. Generally speaking, plants should ask for at least a three to five year battery life. Make sure that your vendors specify battery life at a specific and reasonable update rate. One update every five seconds is a good benchmark for comparing battery life under general usage. Also, inquire about the cost of replacement batteries and if these batteries are standard or proprietary.
Ask yourself what level of a predictable maintenance schedule you require. Certain wireless designs consume battery power at a very deterministic and predictable rate, allowing for scheduled battery replacements. Other designs may consume batteries in a non-deterministic manner, eliminating the ability to schedule battery changes for the system in advance. In order to keep maintenance expenses at a minimum, operators should select systems with predictable battery consumption.
Question #6: How scalable should my network be? How many devices can your network handle? Do not fall into the trap of only considering your immediate needs. To allow flexibility for the future, select a system that can easily scale to thousands of devices.
Ask yourself how scalable you want your network to be. For operators who want to start small and grow, choose a system that is scalable enough to meet future requirements. Some systems can grow very large with minimal performance impact, while other systems quickly degrade after a small number of devices.
Question #7: How many application interfaces should my wireless network serve? Wireless goes beyond supporting legacy devices. Companies also need flexibility to support future protocols that might not exist in the plant today.
Typically, plants contain multiple application interfaces driven by various departments. Many users also want information coming from their wireless devices to use these existing legacy applications and protocols. When selecting a strategic wireless network, you must have the ability to easily interface with all your legacy applications that will require wireless data. This is crucial because this network will service your overall operation, not just one department.
Question #8: Is my network ready for the future? Can the system be easily upgraded in the future? Does it support multiple radios? Wireless systems will continue to evolve and improve in the future. To protect your investment, select a system that can be easily upgraded via software and one that supports different types of radios. This flexibility is critical in ensuring that the system will be ready for the future.
And the answer is… Despite the many benefits, wireless can be a complex enabling technology, and you must carefully research all the options before implementing a solution. If implemented in the correct way, this technology can deliver long-term benefits that directly impact a plant’s efforts to improve safety, optimize the plant and ensure compliance. Industrial wireless networks that do not address each area satisfactorily may not fit your long-term strategic use of wireless technology. W
Jeff Becker is the director of global wireless business for Honeywell Process Solutions and is responsible for all aspects of the wireless business in the organization.