Help needed with PID control of analog valve

[Vorian]

Hi, I'm new here and horribly inept in working with Step7 and i have a problem.

I am trying to use PID control on two analog valves in order to achive steady force on a random surface. My main problem is that I can't get it to work.

My sensor measures from 0-50N and the valves take 0 to 6 bar.

I hve a main OB35 and call a FC which contains the following:

      L     4.000000e-001              // an example of desired value 0.4kg
      T     MD    50

  L     1.000000e+002
      L     0
      -R    
      L     MD    50
      *R    
      L     5.000000e+000  //5 kg maximum
      /R    
      T     MD    54            //set point

 

 L     "sensor"
  T     MW   100   //pv_per

 L     1.000000e+002
      L     0.000000e+000

      -R    
      L     1.000000e-005               // Dead Bandwidth 
      *R    
      L     5.000000e+000
      /R    
      T     MD    58     

 L     1.000000e+002
      L     0.000000e+000
      -R    
      L     5.000000e+000               
      *R    
      L     6.000000e+000
      /R    
      T     MD    62                    //             LMN_HLM 



      L     1.000000e+002
      L     0.000000e+000
      -R    
      L     0.000000e+000              


      *R    
      L     6.000000e+000
      T     MD    66           // LMN_LLM


v1:   CALL  "CONT_C" , DB41
       COM_RST :=FALSE                  
       MAN_ON  :=FALSE               
       PVPER_ON:=TRUE                   
       P_SEL   :=TRUE                  
       I_SEL   :=TRUE                   
       INT_HOLD:=FALSE
       I_ITL_ON:=FALSE
       D_SEL   :=FALSE                 
       CYCLE   :=T#100MS
       SP_INT  :=MD54                   
       PV_IN   :=0.000000e+000
       PV_PER  :=MW100                  
       MAN     :=0.000000e+000
       GAIN    :=6.000000e+002
       TI      :=T#500MS
       TD      :=T#500MS
       TM_LAG  :=T#1S
       DEADB_W :=MD58                   
       LMN_HLM :=MD62
       LMN_LLM :=MD66
       PV_FAC  :=1.000000e+000
       PV_OFF  :=0.000000e+000
       LMN_FAC :=1.000000e+000
       LMN_OFF :=0.000000e+000
       I_ITLVAL:=0.000000e+000       
       DISV    :=0.000000e+000
       LMN     :=MD70
       LMN_PER :=MW110
       QLMN_HLM:=
       QLMN_LLM:=
       LMN_P   :=
       LMN_I   :=
       LMN_D   :=
       PV      :=
       ER      :=MD74


L     MW   110

      T     "V1"                       


  BE

This only for one valve. I can't get the control to work for it at all. I imagine i have some pretty horrbile errors.


Thnx in advance I am getting desperate here!!

 

[JRW]

Can you show us the call for the PID?

Does it write a value for the manual?

 

[Vorian]

You mean the OB35?

A     I      0.0
S     M     20.1


A     M     20.1
JC    ctrl
BE

ctrl: CALL  "CONTROL"

BE