A range of local area network technologies are seeing acceptance in factories, and cellular links are being used to link remote sites to industrial networks.
For many industrial sites, wireless networking provides a quick way to install new equipment or add sensors that provide enhance data collection. These remote sensors can provide more insight into plant operations, measuring factors such as temperature or vibrations. There are a number of options for plant managers who want to add equipment or sensors without running cables.
“The technology is still up in the air,” says Mahesh Patel, director of product management, wireless solutions, for Red Lion Controls. “Bluetooth, ZigBee and Wi-Fi are getting interest, there are still proprietary 900 MHz networks and Hart is being pushed as a standard. I think in the next 12-18 months, you’ll see a predominant technology start coming into focus.”
Often, these sensors are stuck in remote spots that are hard to access. As the problem of routing wires to these hard-to-reach sites fades, the tradeoff shifts to operating lifetimes. Cameras and other sensors that are truly wireless must operate on batteries. The more data the sensor must send, the more users will have to think about accessing it. “How often you talk to the sensors is a key for battery life, which is perhaps the most critical factor for most wireless sensors,” Patel says.
Cellular connections
When communications must go farther, cellular connections often fill the bill. In environments like oil refineries and utilities, sites that are difficult to get to can be monitored all the time instead of waiting until a technician makes a site visit.
“Remote monitoring is one of the more popular applications for cellular (technology). A control station could be half way across the globe but the end user can still monitor the device,” Neteon’s Lee says.
This market is growing fast enough to attract the interest of companies beyond the equipment suppliers who connect telecommunications modules to remote sensors. Cellular providers now view these remote installations as a steady market that might otherwise turn to satellite communications. That’s prompting some to build cell towers that reach distant sites.
“Over the last 18 months, Verizon and AT&T have jumped on the bandwagon, so coverage has become better in remote areas,” Patel says. “If there isn’t cellular coverage, people have to go out and gather the data. With cellular, data collection can go to every couple seconds instead of once a week when someone drives to the site. You also gain the ability to shut off a valve or see that it’s time to do preventive maintenance.”
Remote facilities are not the only industrial sites that employ cellular links. Some plant managers use phone connections to let equipment manufacturers access equipment when it’s time to do troubleshooting or to see if maintenance is needed.
Direct cell phone links let these manufacturers connect to their hardware without using a corporation’s network. That concept can bring significant benefits for companies that have concerns about network security.
“Instead of using the Internet, cellular is used to call the machine builder so they can analyze their equipment remotely,” Hannah says. “There’s been a migration from modems to cellular devices. You can secure the network by letting the equipment makers come in through phone lines. They don’t have carte blanche to access the factory network when they come in via cell phone.”
>> Read our main article from the August 2012 Industrial Ethernet Review: Ethernet Peripherals Increase Industrial Data Accessibility
