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Chapter - Continuous Control

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Presentation on theme: "Chapter - Continuous Control"— Presentation transcript:

1 Chapter - Continuous Control
Examples

2 A Feedback Controller

3 Continuous Feedback - Logical Output

4 Ladder Logic Example

5 Block Diagram

6 An Example

7 Continuous Feedback and Output

8 Proportional Control Equations

9 Modeling Behavior with Differential Equations

10 Implementing the controller in ladder logic

11 Proportional Integral Differential (PID) Control

12 PID Control With Ladder Logic

13 PID CONTROL AND STATUS BITS
pid.CTL:DINT pid.EN:BOOL - the PID function is enabled and running pid.PVT:BOOL - pid.DOE:BOOL - 0=d/dtPV; 1=d/dtError pid.SWM:BOOL - 0 = automatic, 1 = manual pid.MO:BOOL pid.PE:BOOL - 0=independent PID eqn; 1=dependent pid.NDF:BOOL - 0=no derivative smoothing; 1=derivative smoothing pid.NOBC:BOOL - 0=no bias calculation, 1=yes pid.NOZC:BOOL - 0=no zero crossing calculation; 1=yes pid.INI:BOOL - 0=not initialized; 1=initialized pid.SPOR:BOOL - 0=setpoint not out of range, 1=within pid.OLL:BOOL - 0=above minimum CV limit; 1=outside pid.OLH:BOOL - 0=below maximum CV limit; 1=inside pid.EWD:BOOL - 0=error outside deadband; 1=error inside pid.DVNA:BOOL - 0=ok; 1=Error is below lower limit pid.DVPA:BOOL - 0=ok; 1=Error is above upper limit pid.PVLA:BOOL - 0=ok; 1=PV is below lower limit pid.PVHA:BOOL - 0=ok; 1=PV is above upper limit

14 PID CONTROL REALS pid.SP:REAL – setpoint
pid.KP:REAL - proportional gain pid.KI:REAL - integral gain pid.KD:REAL - derivative gain pid.BIAS:REAL - feed forward bias pid.MAXS:REAL - maximum scaling pid.MINS:REAL - minimum scaling pid.DB:REAL - deadband pid.SO:REAL - set output percentage pid.MAXO:REAL - maximum output limit percentage pid.MINO:REAL - minimum output limit percentage pid.UPD:REAL - loop update time in seconds pid.PV:REAL - scaled PV value pid.ERR:REAL - scaled Error value pid.OUT:REAL - scaled output value pid.PVH:REAL - process variable high alarm pid.PVL:REAL - process variable low alarm pid.DVP:REAL - positive deviation alarm pid.DVN:REAL - negative deviation alarm pid.PVDB:REAL - process variable deadband alarm pid.DVDB:REAL - error alarm deadband pid.MAXI:REAL - maximum PV value pid.MINI:REAL - minimum PV value pid.TIE:REAL - tieback value for manual control pid.MAXCV:REAL - maximum CV value pid.MINCV:REAL - minimum CV value pid.MINTIE:REAL - maximum tieback value pid.MAXTIE:REAL - minimum tieback value pid.DATA:REAL[17] - temporary and workspace (e.g. integration sums)‏ PID CONTROL REALS


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