Communications Between Programmable Controllers In The Industrial Environment

As programmable controllers have become more cost-effective and more powerful, they have been used in a larger number of industrial applications. As their use and number has increased, a strong need has arisen for a simple cost-effective means of communications between programmable controllers. Local area networks are a recently developed solution to the problem and appear to provide a communications network for true factorywide automation. The performance requirements of such a local area network, when used in industrial applications are discussed along with the design alternatives that must be considered and resolved. Particular emphasis is place on the reliability implications of various implementation schemes. An example of a local area network used to communicate among programmable controllers in order to control an industrial process is included.