adam_ski

Does anyone have a sample program or idea how to control the flow with a diaphragm pump using S7-1200?

I have a flow meter that gives an analog output proportional to the flow rate and pulse output per quantity of liquid. Pump is controlled by a solenoid valve so I get flow once the solenoid is energized and once when it is de-energized. Time ON and OFF have to be symmetrical so PMW doesn't seem to be the answer since there the cycle is fixed and only time ON changes (if I understand PMW correctly).

Can anyone help please?

Thank you,

Adam

Hi Adam,

So what you hoping for is to have a variable frequency pulse, also called PTO (pulse train output). There will be a limitation to the frequency to what the pump mechanism can handle. Do you have an idea to what this would be?

The rate of the ON and OFF should be low enough for you to code the pulse with IEC timers. Look at https://support.industry.siemens.com/cs/ww/en/view/54647747.

Alternatively you can use the motion control technology function. You use the JOG instruction to get the proper on-the-fly frequency adjustment.

Is that what you were hoping to find?
w