Back in the ’90s Profibus and Foundation fieldbus competed to replace 4-20 mA communication for field devices like valves and process transmitters with all-digital systems. This was supposed to save a great deal of money on cabling and make possible a new world of smart field devices that could be diagnosed and recalibrated in the field. HART, which put a digital signal on top of the existing 4-20 mA loop, was already there but was considered outmoded by promoters of the new buses.

Years later all three are still here, and now the battle is over the use of wireless networks in industrial settings. There’s WirelessHART, ISA100.11a, WiFi and the list goes on. It can be difficult to figure out which network is best suited for a particular application, and this isn’t helped by the fact that it’s difficult to figure out what standards govern them. This article will help to sort out the alphabet soup of different wireless standards.