Equal Percentage Valve control.

How would I convert the 4-20mA analog output from logix5000 so that the ouput becomes non linear thus turning the actual action of a equal percenatge valve into that of a Linear valve.?????????

Use a program (see link below) to create a nth degree polynominal. The results of which is the output to your valve.




http://curveexpert.webhop.net/

It's a logrithmic function so you will need a pretty high order polynomial to fit the curve.

The equal percentage function is well defined mathematically. Take a look here. I would put the equation in the plc and scale it that way.

Keith