Split range control


Split range control is used when two actuators are present. Usually one valve with fine and one with coarse resolution. Combination of such actuators allows to increase the PID control accuracy even within small values of the manipulated variable.

The comparable approaches are FLOATING CONTROL and CENTER-SEEKING CONTROL. However, these latter methods have the disadvantage that they do not allow to open and close coarse valve rapidly.

In this simulator, blocks CNDR_FINE and CNDR_COARSE define way how manipulated value is "split" into interval from zero (fully-closed) to one (fully-open). The model of the process (blue blocks) assumes that all valves are controlled by exact position, otherwise it would be necessary to use SCU or SCUV block to control valve with logical signals UP (more) and DOWN (less).

How to start the simulator?

Before starting the simulator (applet) by START start.gif, 648B button, the sampling period can be set in the field Sampling time. The continous applet running can be stopped by STOP stop.gif, 666B button or paused by PAUSE pause.gif, 1,1kB button. The simulation speed can be adjusted by the slider. The re-init button reinit.png, 858B reset all parameters to initial state.

All parameters of active blocks (non-shadow) can be changed in the dialog which is invoked by cliking at the block. Detailed description of block parameters is available in Function blocks reference manual.