RS-485 Serial Data Communication
Physical Layer for Factory Automation and Process Control Networks
by Mark Hazen, High Performance Analog
Intersil Corporation
Today, there are some predominant and widely-deployed factory automation and process control networks, such as PROFIBUS and Field Bus, which employ RS-485 (EIA-485) serial data communications transceivers, and the 485 standard, in the physical layer. These transceivers enable control of manufacturing and other processes over a wide area, such as the factory floor (field), from a central computer control station. The simple twisted-copper-pair network wire (bus) snakes its way around the plant (field) throughout the machinery to a host of sensors and actuators that the computer uses to direct and syncopate a myriad of operations that yield a final product. Already you can see the derivation behind the popular network name, Field Bus.
The elegance of such a network is found in its low cost, simplicity,
extensibility and very high noise immunity, in addition to the tremendous
selection of sensors and actuators readily available to bring the network
online quickly. PROFIBUS is an industry name coined from Process Field Bus.
The PROFIBUS association is made up of over 1200 members internationally
and is responsible for thousands of software and hardware network automation
products.
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