Siemens Module B3 ユーザーズマニュアル
Automation and Drives - SCE
T I A Training Document
Page 37 of 64
Module
4. CONTROLLER BLOCK (S)FB41 "CONT_C" AS SOFTWARE PID CONTROLLER IN STEP 7
4.1 Task Definition for PID Standard Controller
In this B3 module, the startup of a PID controller in SIMATIC S7 is demonstrated. The output value
of the controlled system is to be kept constant with a continuous controller. Depending on the
setting, the controlled system can simulate a P, PT1, or PT2 system. The transfer coefficients Ks
and the time constants can also be set. (refer to the description of the controlled system).
Thus, the PLC is the controller, and is connected to the controlled system by means of analog inputs
and outputs.
The block (S)FB 41 in the PLC SIMATIC S7-300 is used in this task as a continuous digital software
controller. It is to solve the control problem as follows: an analog manipulated variable y is read out
depending on the respective setpoint/actual value w-x. The manipulated variable y is generated
according to the PID algorithm.
The following control parameters can be specified:
KP: Proportional component (for (S)FB41 Gain)
TN: Integrator time (for (S)FB41 TI)
TV: Derivative time (for (S)FB41 TD)
Preface Fundamentals Discontinuous Action Controllerr Controller Block (S)FB41 Setting the System Appendix
B3
Issued: 02/2008 Control Engineering with STEP 7