PLC-API Requirements 5.4.9 FB_CTRL_PID The function block provides a PID transfer element in the functional diagram. Transfer function: The following transfer function can be declared for this block, if the boolean inputs bPInTheFeedbackPath and bDInTheFeedbackPath are set to FALSE, otherwise this transfer function only describes a part of the blocks behaviour: Functional diagram: The standard functional diagram of a PID controller in additive form has been expanded by the two active boolean inputs bPInTheFeedbackPath and bDInTheFeedbackPath (which act as "switches"), so that a modified functional diagram can be activated. Control background:
due to the differential component of the control algorithm, large control values are generated at setpoint step-changes, which cause a strain on the control elements and may cause the control system to oscillate. A control algorithm with a differential component that is only applied to the controlled variable ( bDInTheFeedbackPath := TRUE ) can avoid this problem. The bPInTheFeedbackPath and bDInTheFeedbackPath inputs permit the closed control loop to implement the following transfer functions: TS4100 57 Version:
1.1 Development Environment Target System PLC libraries to include TwinCAT v2.8 PC (i386) TcControllerToolbox.lib TwinCAT v2.9 from Build 947 BC [} 10] TcControllerToolbox.lb6 TwinCAT v2.9 from Build 956 BX [} 10] TcControllerToolbox.lbx