Find your way through the wireless maze
For those grounded in wired networks, untangling wireless-related issues for plant-floor applications can be as intimidating as reworking networked I/O connections without documentation. If you haven’t jumped into wireless communications yet on the plant floor, or even if you have, here are some questions and answers to help clear the air about wireless.
For those grounded in wired networks, untangling wireless-related issues for plant-floor applications can be as intimidating as reworking networked I/O connections without documentation.
If you haven’t jumped into wireless communications yet on the plant floor, or even if you have, here are some questions and answers to help clear the air about wireless.
Providing answers are:
Bob Gardner , Banner Engineering, SureCross wireless product manager
Jim Toepper , Moxa Americas product manager, connectivity group, industrial wireless group
Robert Jackson , National Instruments senior product marketing manager, wireless
Paul Brooks , business development manager, networks portfolio, and Cliff Whitehead, manager, strategic applications, Rockwell Automation.
A plan for the wireless deployment’s scope throughout the installation’s life cycle
A baseline survey of the radio frequency (RF) environment in and near the deployment areas, including during lift truck transportation, material movement and other environmental conditions.
Users should leverage professional expertise as well as tools such as access points to detect rogue devices, and advanced modeling software to map expected radio strength and eliminate coverage gaps
A plan to perform periodic baseline survey updates that help adjust to changing RF conditions.
Q. Can a wireless site survey help? A plant floor can change quickly.
Toepper : Before deploying a wireless solution, know your environment. Site survey software tools available on the Internet may require a laptop or computer to measure the wireless signal. Most of the time in the industrial environment, it isn’t your laptop’s radio that needs the wireless connection.
Be sure to measure signal strength using the radio and antennae of the wireless clients in the location throughout the time it will be used. Because radios differ in power, and antennas have different gains, it is more accurate to do a site survey this way.
Hardware with a signal meter on it provides an advantage, making it easy to glance at signal strength bars.
Gardner : Some manufacturers have equipped wireless devices with an onboard site survey capability. Of course, plant environments and conditions change, and it is important that any wireless network you purchase has a strategy for identifying areas and times when the link is weakest.
Some site survey tools use a separate communication layer than the I/O signals being collected. This enables the wireless network to perform its required task while monitoring its own radio frequency (RF) communication link.
<table ID = 'id2347014-0-table' CELLSPACING = '0' CELLPADDING = '2' WIDTH = '100%' BORDER = '0'><tbody ID = 'id2347264-0-tbody'><tr ID = 'id2347266-0-tr'><td ID = 'id2346780-0-td' CLASS = 'table' STYLE = 'background-color: #EEEEEE'> Author Information </td></tr><tr ID = 'id2346789-3-tr'><td ID = 'id2346792-3-td' CLASS = 'table'>Naoki Yamaguchi is assistant technical manager for NB Corporation of America in Hanover Park, IL. Reach him at firstname.lastname@example.org .</td></tr></tbody></table>
Q: Is wireless networking ready for prime-time factory applications?
Gardner : Yes! My garage door has been wireless for more than 20 years, not to mention the WiFi connection built into my laptop. To implement wireless in plant environments, factories require reliable deterministic signals with a known output condition if an error were to occur.
Wireless communication of I/O and serial data is the next step for plants that want to optimize resources and ensure all assets are performing at peak capabilities.
Jackson : Wireless is ready for a more central role as an add-on system to the existing wired infrastructure. This ability to combine wired and wireless measurements will allow end users to preserve investments and use wireless technology in applications where it makes sense.
Q. What are some common uses for wireless networks in a factory?
Brooks and Whitehead : Today’s wireless deployments generally occur in applications where wired networks present challenges, making wireless increasingly simple and cost-effective. With its periodic signal monitoring and data collection capabilities, wireless also becomes increasingly valuable to mobile workers. While wireless can improve cost and operational efficiencies, it does not necessarily make deployment easier.
Q. In a wireless implementation, what should a user, original equipment manufacturers (OEM) or system integrator consider?
Jackson : The correct wireless protocol depends on the application. Software working at the application layer helps a system support multiple protocols. This allows users to combine the advantages of different protocols, and better isolates them from technology evolutions.
A tiered strategy to wireless network support may provide the best service to a broad set of applications. Offer a tightly integrated hardware/software solution for industry standards, such as Wi-Fi, for the best end user experience.
At the same time, provide support for proprietary and emerging standards through software abstraction, so end users can preserve software investments while maintaining flexibility as protocols change.
For instance, wireless data acquisition can use Wi-Fi for easy connectivity and high bandwidth measurements. Software drivers [or other tools, such as OPC servers] can connect applications to a range of proprietary wireless sensor network (WSN) nodes from third-party suppliers.
Q. What’s needed for a wireless implementation?
Brooks and Whitehead : To help enhance the success of an industrial wireless installation, it should include the following features: