How does a FB41 block D-part work ?

Hello, everybody !

A  FB41 block, I currently use, has P- and I- parts.

I want to add D-part.

Tell me please, if the D-part works when PV is inside the DeadBand ?

Alex3110

A  FB41 block, I currently use

 Hello Alex3110,

sorry but FB41 PID block in S5? 

Sorry, take a look here

https://www.fer.unizg.hr/_download/repository/S7pidcob.pdf

Alex3110

Sorry, take a look here

https://www.fer.unizg.hr/_download/repository/S7pidcob.pdf

  Hello Alex,

  This is for S7 system and not for S5, but no problem,

  I ask the moderators to move this thread in the right conference

Alex3110

Hello, everybody !

A  FB41 block, I currently use, has P- and I- parts.

I want to add D-part.

Tell me please, if the D-part works when PV is inside the DeadBand ?

 Hello Alex;

Look at the flowchart from the document you posted, describing how parameters of FB41 are linked to the process control for answers to your questions:

- You have P and I actions in a standard way because the parameters P_Sel and I_Sel are set by default in the FB41 (it is by default a PI controller algorithm). To add derivative actionyou must set D_Sel, and then estimate adequate values for TD (the derivative time constant; greater than the Cycle parameter value)  and TM_Lag (used if your process shows a significant delay; should be greater than Cycle/2) for your PID controller to work properly.

- The deadband is not applied to PV, but on the error signal (SP - PV); and therefore the deadband limits the range of error that will affect the intervention of parameters P, TI and TD. While the error signal is inside the deadband, no change of output signal will be calculated (the error is considered to be zero).

Hope this helps,

Daniel Chartier

Thank you very much !