Compact controllers are independent control devices which can control one or several control circuits. The controllers can be freely parameterized and can thus be adapted to any type of control loop. Simple versions have a numerical display of the process values. Compact controllers in high-end equipment are available with touchscreen and graphical representation of the control loop or the system.
In addition to the actual control loop, compact controllers can also take over control tasks and thus control the process sequence or parts thereof independently. Compact controllers can be found in almost all industries. For example, the program controller function is often used in the food industry, or in hardening to define specific temperature profiles.
Compact controllers are either fixed or modular and can therefore be extended. The analogue inputs for the actual value are often universal and can be configured for different types of sensors and signals. Digital inputs are also available for the detection of switching operations. Various binary switching elements are available as outputs, such as relay, semiconductor relay, logic and MosFET outputs, and are used either for controlling binary actuators or for control signals. The analog outputs can be configured as voltage or current output, e.g. 4 ... 20 mA / 0 ... 10 V and are used for the continuous control of analog actuators such as, for example, proportional valves, thyristor power controllers or frequency converters.
The operation, parameterization and configuration can be carried out via the device front, in addition, configuration programs are supplied in which the settings for the user can be clearly arranged. The connection between PC and controller can be established via USB, TCP / IP or serial interfaces.
Depending on the configuration of the outputs, the following controller types can be configured.
The program controller function provides the controller with a setpoint profile defined by the user, which is divided into several sections. The controller then no longer operates with a fixed setpoint, but receives this from the program. The system can thus approach specific setpoints at defined times. In addition, the individual sections can be assigned with control contacts in order to drive additional actuators.
In the case of compact controllers with a color display, a recording function is often available in which important process data are recorded and archived.