 Here you will find a simple PI imitator for control valves.
 Buttons "A"  - for changing state (automatic or manual) 
 of valves (FRC1 and LRC2).
 Buttons "1/40 sec", "1/10 sec", "1/2 sec", "0 sec" - for
 changing frequency of calculations. Buttons "G1",...."G2" -
 for displaying graphics of desired variables:
    PV FRC1  quantity of liquid through the  pipe 1
    SP FRC1  set point for PV  (editable 0-100)
    MV FRC1  output
    P FRC1   proportional coeficient of PI formula (editable 0-100)
    I FRC1   integral coeficient of PI formula     (editable 0-100)
    TL FRC1  for imitation pipe 1 (editable 0-100)
    IP FRC1  integral part of PI formula
    PP FRC1  proportional part of PI formula
    BP FRC1  BIAS of PI formula
    PV LRC2  level liquid in reservoir
    SP LRC2  set point for level (editable 0-100)
    MV LRC2  output
    P LRC2   proportional coeficient of PI formula (editable 0-100)
    I LRC2   integral coeficient of PI formula     (editable 0-100)
    TL LRC2  for imitation pipe 2 (editable 0-100)
    IP LRC2  integral part of PI formula
    PP LRC2  proportional part of PI formula
    BP LRC2  BIAS of PI formula
    GV LRC2  quantity of liquid through the  pipe 2
    KR       for imitation the capacity of reservoir (editable 0-20)

  Size=  800*600 pixels
  Font - ARIAL