Hi all,

I am measuring pH and reading via an Analogue input.
I have a setpoint that the pH should be, and I want to generate an error when the actual value is 10% below/above the SP.
Can anyone point me in the right direction as to how to code this?
I am using a SLC500.

Thanks, Conor

Error = SP*1.1 or SP*.9.

You could place these two values in a LIM instruction or put the SP*1.1 in a GRT and the SP*.9 in a LES.

See attached, in this example F8:0 contains your PH setpoint, F8:10 is the scaled value from your analog input. I used two compares, because you may want to know if its high or low also.

Ken

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