PID ignoring Ti and Td

[Jochem]

Hello all,
I am trying to use the PID.vi delivered with the addon toolkit but it is not working out very well.
It seems that the PID is ignoring all input from the Ti and the Td, doesn't matter what I put in there no reaction at all.
To test it I build a very simple loop with in there only the PID and a graph to visualise.

These are the settings:
Setpoint = 30
Kc = 1 Ti = 0,5 Td = 0,1
output range from 0 too 100 (%), dt = -1 default internal clock, beta = 1, linearity = 1, Reverse = T, Auto = T.
Most of them the default values.

Running the VI (with a permanent offset) should show some integral action, nothing!
Changing the Kc does have affect.

I am missing something big time here, it must be. I worked with PID a lot before but thi
s is new for me and starts to frustrate me a little.
Hope you people can help me back on the track again..
Jochem

[Ben]

I do not have that tool kit loaded on this machine so I can not double check.

I believe there is an input to that VI that initializes the time dependent stuff. Is that set correctly?

Just guessing.

Ben

[Jochem]

You are completely right. For the PID it is necassary to wire the iteration input.
The reason why I did not wire it at first is that the control loop will propably run for months and might exceed the maximum iteration value. Looking into the diagrams made it clear that a value bigger than zero will do the job and has no further impact. (I know the concequences of using a constant)

I really missed something this time.. Thanks for helping me out.
Jochem

[Ben]

No problem.

Questions like that out of the blue keeps me thinking.

Ben