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PID - P1 is working and i can allow changes to control value but P2 is working but will not changes to control value - It is READ ONLY


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Help me guys please


I have two control loops PID P1 and P2

P1 is working fine and it has logic to store 0 to  "control value"  without compiler faults

P2 is working fine but it wont allow store 0 to  "control value"  , system  responds  compiler "tag is read only"

Now i am thinking that P2 is wrong so i create a P3 and its the same P2 but it wont allow store 0 to  "control value"  , system  responds  compiler "tag is read only"

when i duplicate P1 to  P11 ,  the P11 acts the same as P1 and it compiles ok and store 0 to "control value"  without compiler faults


Now i am sure the logic should not allow me to store 0 to "control value" and the compiler  is right but why does it work fine on P1 but it wont work on P2


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Hello @hamfam,

The member "control value" is actually supposed to be read-only.

When reopenning your project, and compiling with "Rebuil All", does the assignment still pass compilation?

Did you create P1 and P2 at about the same time?

I guess any "PID config" struct that you create from now and then gives a compilation error on such an assignment, right?

I suggest you to send your project to R&D (through support), it looks that the P1 tag is somehow corrupted. (you don't really have to, if you wish, you can just create a P3 variable, use the find & replace feature to replace all P1 occurrences with P3, delete P1, then rename P3 to P1)

Hope that helped you

Best regards,



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