When the first programmable logic controllers were used in production fifty years ago, they had one objective: to provide an electronic and freely programmable alternative to the failure-prone relay. Up until this point, relays had controlled all the automatic processes of a production line – in a similar way to their function in the Konrad Zuse’s first binary computer, the Z1.
What followed were durable, compact units which could be distributed around the plant and linked by means of networks. Initially, these were proprietary networks which afforded little compatibility to the devices supplied by other manufacturers. But still, the use of distributed intelligence represented an enormous step forward in the development of machine and plant engineering. The precision, speed and durability with which processes could now be controlled were also impressive. Since this time, automation systems have controlled not only robots, machine tools, agitators and filling stations, rotary kilns, sewage pumps, rolling stand drives, paper machines or trucks used in open-cast mining, but also turbines and generators, power distribution plants and traffic lights. In short, automation technology is in use everywhere, in every factory, in every infrastructure facility and every building.
The connection of different devices to each other using field bus systems represented an important leap forward in innovation. This development was driven by the need to reduce wiring costs. Using a single thin two or four-wire cable, it was now possible to transmit signals within just milliseconds, paving the way for significantly faster response times. It was this development twenty years ago which laid the foundation for digital communication in the industrial environment. The world of automation, which had previously been purely proprietary, was opened up to the wider public by the advent of today’s standardized field buses.