Conventional PID controllers are frequently used in manual mode in practice because the control quality achieved does not match the expectations. This is because either the controllers have been poorly set or because the processes are difficult to master using PID controllers, for example,

• Temperature processes
• Processes with a high percentage of dead time
• Processes which change depending on time or operating point

The optimum setting of PID controllers additionally requires special experience and is very time-consuming.

A recommendable alternative for solving such problems is the adaptive controller ADCO. It works on the basis of a process model which is determined in the background during the adjustment process. Using this process model, ADCO can predict the result of a process intervention (predictive controller), for example, how the opening of a steam valve by a certain amount will affect the process temperature. In the opposite direction, it is also able to determine the valve position required to achieve or retain a defined temperature value. ADCO with the process model has more process information available than conventional controllers, and uses this to improve the control quality.

Combination of single views from ADCO

ADCO is also available as a multi-range controller (ADMR) up to SIMATIC PCS 7 V8.0. The special feature of this version is that is the control range can be divided into a maximum of 8 zones which can be individually optimized. Switching over between the zones can be carried out by the user or is event-dependent.

Note:

The adaptive controller ADCO can be used together with SIMATIC PCS 7 V7.1, V8.0, V8.1 and V8.2.