PID Equation -- Bailey Function Code FC156 Independent Form


Thread Starter

Danyang Liu

I have got two different PID equation descriptions for Bailey Faction Code FC156 Independent PID:

(1) Kp + Ki/s + Kd*s/(1+Kd*s/Ka)
(2) K(Kp + Ki/(60*s) + 60*Kd*s)

where Kp the proportional gain (no unit), Ki integral reset (per minute), Kd derivative gain (minutes), and K gain multiplier.

Which one is correct? If both are wrong, what is the correct equation then?

Winston Smith

Both the equations seem to be incorrect. The recent Bailey 'Helpdesk' CD (about 220Mb) has full details of the equations used by FC 156.
Please do not panic yet !!!

Winston above is wrong.
These two very short form equations are both right.
The first one is the non interactive PID.
The second one is the interactive.
The only difference between the two are the tuning
parameters have a different relationship (based on the traditional Ziegler Nichols method).
The block FC156 is a very advanced PID.
FC157 does straight simple PID.
A little bit of diagramming is required to show the tuning parameters. As this is not feasable
on that forum let me know for more on that.
[email protected]