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Author Topic: PID Output Turns Off?  (Read 6513 times)

stgislander

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PID Output Turns Off?
« on: March 31, 2023, 06:31:44 PM »
I was doing some testing of a PID loops in my Do-more project.  I'm using the H2-DM1E CPU and two F2-02DA-2L analog output modules in bipolar mode to drive servo valves.

I discovered that when MyPID.Output reaches 100%, the analog output voltage drops from approx +2.5V to 0V.  What I find interesting is when .Output reaches 0%, the analog output holds a steady -2.5V.

Is the drop to 0V at 100% output normal, and do I need to limit the PID .Output value to 99.x%?

stgislander

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Re: PID Output Turns Off?
« Reply #1 on: April 01, 2023, 09:40:28 AM »
I found the problem.  After a little time away from the problem, I discovered that I had typed 2048 into the "Scaled Max (100%)" field in my PID controller setup.   It didn't dawn on me that was the problem until I pulled up the D2 Analog Manual.  In Chapter 9 bigger than life was a warning not to exceed 2047 when writing to the DA mobule.

BobO

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Re: PID Output Turns Off?
« Reply #2 on: April 01, 2023, 12:13:14 PM »
Great!
"It has recently come to our attention that users spend 95% of their time using 5% of the available features. That might be relevant." -BobO