Technology and Application
The best way to control your plant
In the beginning, production is the reason why factory plants do exist. Controlled by a supervisor raw materials are formed and treated by all kinds machines and apparatus to make the desired products. Key-element in the control of a process is the interfacing of the machines and apparatus with the supervising level.
In the early years of the PLC, PLC-cabinets with many terminal blocks were common. One disadvantage of the centralized cabinets came clear, to connect every sensor and actuator in the field to the central control PLC, many cables of great lengths were needed.
Remote-I/OWith the development of fieldbusses also came Remote-I/O. The terminal blocks now could be placed closer to the sensors and actuators in the field. This drastically reduced the length of the connection cables. But, with an even slightly increasing number of cables, there are no savings on installation time.
AS-InterfaceThe next (and final) step in evolution brings the AS-Interface fieldbus in combination with dedicated AS-Interface modules like Valve-controllers and Motor-controllers. A unit like a Valve-controller has everything inside for the actuation and position feedback of the valve it is mounted on. The data and power for up to 62 AS-Interface units is supplied by the AS-Interface fieldbus using just one cable. Savings in installation time and money vary with the size of the process plant, common savings are between 40% and 60%.