The International Society of Automation (ISA) has published a fourth edition of its book on wireless networks for industrial automation, updated with an analysis of today’s newest wireless technologies.
Wireless Networks for Industrial Automation, Fourth Edition by Dick Caro, provides an unbiased view of the emerging wireless communications market.
It examines the latest advances in wireless technologies for process control, such as ISA100 Wireless (ANSI/ISA-100.11a), WirelessHART, WIA-PA and WiFi, including IEEE 802.11n and 802.11ac.
Caro is an ISA Life Fellow and industrial automation consultant at CMC Associates.
“A lot has changed in the marketplace since the third edition of my book was published,” notes Caro, an expert in industrial networking and current chair of two ISA100 Wireless standards subcommittees.
“At that time, ISA100 Wireless was just being developed and WirelessHART had just been announced. This new edition covers their transition to well-established, proven standards, and provides guidance to those seeking a comparison of the two."
Since both ISA100 Wireless and WirelessHART have well-documented field experience and installation success, Caro says that both can be utilised without trepidation of any kind.
“Today, both are absolutely reliable, secure and simple to install, and since their batteries seem to last forever, fears of battery replacement have disappeared,” he asserts. “At the same time, they both have differences.”
ISA100 Wireless, he explains, is particularly valuable to “those forward-thinking process control users who can visualise a control system architecture that includes plant-wide wireless control networks.
WirelessHART has been important to some users who have urgent needs for measurements or status detection in areas that have been too costly or unable to connect wired instruments or sensors.”
WIA-PA, Caro indicates, was developed at a Chinese university and it is not known if there are any commercial applications within China, and, to date, none have been offered for export.
He says that IEEE 802.11, on the other hand, has been in active development for many years, and is widely installed in many manufacturing locations where wired or fiber optic Ethernet may have been used.
“Wireless offers installed cost advantages,” Caro points out. “When the third edition of my book was released, IEEE 802.11n had not yet been ratified, but vendors were already selling product.
"Now, IEEE 802.11n is the Wi-Fi market leader with many installations of the MIMO (Multiple-Input Multiple-Output) form with dual frequencies to provide spatial diversity.
"Today, IEEE 802.11ac is nearing ratification and suppliers are already selling product. As improvements to IEEE 802.11 are made, the speed increases to the point that IEEE 802.11ac will achieve speed parity with wired gigabit Ethernet.”
Caro says some vendors of wireless process control systems, instruments and network devices tend to “over market” their products, making claims for features that are not incorporated or sometimes not even planned for the future.
“I hope that this updated edition can help users make intelligent decisions that will enable them to plan future process control networks and control system architectures in which wireless is certain to play a major role,” he concludes.