Справочник Пользователя для Siemens Module B3

 

 

 

 

 

 

 

   

 

 

 

 

T I A  Training Document 

Page 57 of 64 

  Module 

 

To accommodate the system step response, a few modifications have to be made in OB 35 and 

DB41. The following steps have to be performed for this: 

Save your old project under a new name, and change the wiring of (S)FB 41 as follows: 

1. With STEP7, specify the manipulated value directly.  

The manipulated value is to be specified in the network below in a way that with a switch  

S1 (I 124.0), a selection can be made between two manipulated values. 

 

 

L 

0.000000e+000  

//Manipulated value 0% as 32 bit floating point number 

 

 

UN 

I 124.0   

 

//Negation of S1 (I 124.0) 

 

 

SPB 

M001   

 

//Jump if RLO = 1 to label M001 

 

 

L 

1.000000e+002  

//Manip.value 100% as 32 bit floating pt. nbr. 

 

M001: 

T 

MD 20   

 

//Transfer the value to flag double word MD 20  

Now, for the switch position S1(I 124.0) ON, the manipulated variable y = 100%, and for OFF, the 

manipulated variable y = 0%. Consequently, a step of the manipulated value from 0 to 100% can be 

brought about with Switch S1.  (For systems that tend to overshoot, the high manipulated value 

should amount to 90% or less.). 

The external analog values and the manipulated value are assigned in OB1 as follows:   

 

MAN 

 

:= 

MD 20   

//Specify the manipulated value as manual value 

 

PV_PER 

:= 

PEW 130 

//Actual value x 

 

LMN_PER 

:= 

PAW 128 

//Manipulated variable  y 

 

 

 

 

 

 

 

 Switch manipulated value to manual 
mode

 

 

 

 

 

 

 

 

Preface    Fundamentals     Discontinuous Action Controller     Controller Block (S)FB41     Setting the System     Appendix 

B3 

Issued: 02/2008                                                                                                                                     Control Engineering with STEP 7