But many observers feel the wireless boom may breathe new life into some architectures. Though these fieldbuses have been around for a long time, they are adapting to the new world of wireless communications.
While fieldbuses are often phased out for newer technologies such as industrialized Ethernet, wireless is providing a new channel for the protocols. Many of the input/output (I/O) points that remain a bastion of fieldbus usage could benefit from the ease of installation provided by wireless technologies.
监督各种现场类别的组织正在进行，以确保其技术适应了无线通信的快速扩展。“所有FieldBus联盟都在寻找确保其协议通过无线网络运行的方法，”卖方Rockwell Automation Inc. Mayfield Heights的Cliff Whitehead说。
Which wireless scheme they tap is an open question. A range of proprietary networks and standards such as ZigBee are vying for acceptance. Wi-Fi has gained acceptance because it’s compatible with Ethernet backbones. Even Bluetooth, normally associated with cell phones, is getting some interest.
“无线不是解决方案，而是解决方案的范围，”位于宾夕法尼亚州米德尔敦的Phoenix Contact Inc.的自动化系统营销经理Greg Dixson说。“我们可以将蓝牙与现场总线和工业以太网一起嵌入背板中。通信可能在10毫秒以下发生。蓝牙提供高速，低成本和短距离。”
易于安装的无线是一个关键的好处links, which give engineers the ability to install sensors or other products in locations that would be difficult to wire. “A customer had a rotating table that made it impossible to connect though hard wires. We used a Wireless Adapter to connect a CPU (central processing unit) on the rotating table with the main CPU,” says Stephan Stricker, product manager at vendor B&R Industrial Automation Corp., in Roswell, Ga.
Suppliers also note that these links offer far higher bandwidth than conventional fieldbuses, giving users the ability to gather more data. “There are large numbers of Hart devices installed in the field, but a relatively small percentage are extracting all the rich Hart data because they’re tied to 4-to-20 milliAmp (mA) wiring,” Whitehead says. “People are putting wireless dongles on so they can get all the data that’s available.”
尽管无线链接更容易在很难安装新布线的工厂中安装，但这并不意味着它们很容易。可靠性是一个很大的问题，直到成功的应用程序数量证明即使在苛刻，嘈杂的工厂自动化世界中也可以计算无线。了解无线技术的环境和功能是成功部署的关键之一。
怀特黑德说：“您需要花更多的时间制定一个好的计划，而不是进行有线网络。”“您需要了解工厂中的频率是动态的。墙壁移动，设备移动。您需要一个好的计划，需要确保每个人都理解它。”
Once installations are up and running, they can usually be forgotten, much like wired networks are considered a basic infrastructure element that simply works. “Wireless nodes can be fairly low maintenance items. You just check them every four or five years to see if the battery is working OK,” Whitehead says.
Related Feature - Still Playing the Field
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