Hi to all!
I am new to unitronics and PID, serched on internet how pid works and i understood theory well, but.....
I've have idea to controll 3ph motor inverter with analog output from PLC (0-10V will be 0 to full rpm) and feedback to plc will be proxy sensor which will send impulses to HSI input of plc, and set value which will be entered to plc.
So far i am trying to use PID example from flow controll, but no mather what i put in as values or what input is (frequency) i do not get anything to analog output.....in short, my idea was this:
When motor is not running i should have max value on analog output, so 10V, when i start inverter set ramp will gonna try to rotatate motor to max, since i read impulses as frequency, when we reach impulses to be same as set point controller should start to lower analog output so to negative feedback start working and controll rotation in such way.....so basicly, on max rpm i will have something like 100Hz from proxy switch to plc, when motor is stopped i shoudl have 10V on analog output, and proportionaly while input frequency is rising up i should have lower analog output.......later i can do scaling values to fit my range.
To start now, what is best possibly way to do this, as i can see PID function? Since, i can have some +/- 1-3% offset from nominal i would like to start with P (proportional) function only, but do not know how to set PID to work as P only?
best regards,