PID Setpoint Profile

[Allen87113]

I am presently trying to use a PID loop to control a tube furnace. I have the loop and PID working properly. I used the Setpoint Profile Simulator VI as a basis for my work. The problem I have is that I am having difficulties with the loop terminating prematurely when I

enter in my own profile. Also, what are the rules/advice for feeding a profile into a PID Setpoint Profile vi and then into the PID vi?

I can provide my example code if needed.

Thank You,

Allen Schult

Cabot Corporation

[GiGe]

Hi Allen,

What values are you entering into your profile?  The loop shouldn't stop until it has completed your profile (if you are using the Setpoint Profile Simulation.vi).  The only "rule" would be that the time values need to be greater than or equal to the previous value.  Although that won't cause your loop to stop prematurely.  What is wired to your conditional statement in your while loop?  Make sure that it is wired the same as in the setpoint profile simulation.vi.

Have a great day,
GG

[Allen87113]

GiGe, thank you for the response. I do understand that I need to put the values into the profile array in ascending order. Essentially what I have done is copied the code from the setpoint profile simulator exactly removing the "plant" and substituting my own process. Even when I input my profile into the simulator the simulator does not run. Attached is a copy of my test profile for review. Maybe you can see what I am missing.

Thank You,

Allen

[GiGe]

Hi Allen,

I just entered your points into the simulator and I got it to run, but I think I know what the problem is.  The simulator is using more points then you were, so if those last two points are set to 0 then the vi won't run.  If those last values are set to 3300 then the VI should run just fine.  Let me know if that helps.  What this example does is looks at the last value in the profile and then it will run for that long. 

Regards,
GG

[Allen87113]

GiGe:

Thanks, that helped out a bit. It is sometimes a bit flaky, but  I am working on it and can live with it.

Thank You,

Allen