How can I use PWM to control a Solenoid Valve through a PLC?

I am looking at controlling the flow-rate of one liquid through a Solenoid Valve in a closed loop system, which takes input from another stream of liquid.

Objective is to mix the two liquids at the right concentration downstream.

I was able to source a PWM enabled valve, but how do I send the PWM signals to the valve? I have read about Controllers and Drivers, but don't understand too much as I am not from an Electronics background.

Any guidance would be appreciated. Thanks

Most PLC have an analogue module.
But without the right kind of module, PLC's were not originally built with PID loop features etc . Due to the slow scan time.
You would need to find out if the PLC you are using has a PWM module available.
Max.

kunalv said:

I am looking at controlling the flow-rate of one liquid through a Solenoid Valve in a closed loop system, which takes input from another stream of liquid.

Objective is to mix the two liquids at the right concentration downstream.

I was able to source a PWM enabled valve, but how do I send the PWM signals to the valve? I have read about Controllers and Drivers, but don't understand too much as I am not from an Electronics background.

Any guidance would be appreciated. Thanks

Click to expand...

Inline proportional metering With valves is usually avoided in process control system.

Usually, pump speed control is much more accurate (depending on pump technology) and,
even better is small mix tanks that can be dosed with the right ratios and recirculated to achieve the right ratios (unless reaction starts upon mixing).

The project engineers and their bean counters seem to think minimizing capital investment Can be achieved by using inline blending/mixing but the savings are usually lost when the production starts and you need to adjust batches or dispose batches because of mixing inaccuracies. Worst case is when you have to pay for your customers to empty their tanks of off-spec raw materials that got through your system or recall their product.

Hey, good luck.

gophert said:

Usually, pump speed control is much more accurate (depending on pump technology) and,
even better is small mix tanks that can be dosed with the right ratios and recirculated to achieve the right ratios (unless reaction starts upon mixing).

Click to expand...

That's how we did it to obtain the right PH level prior to discharge into the storm serer system.

It would help to have a link to your valve and a detailed explanation of your goals with the project. You have a proportional valve and ?...

Ron

There are pwm modules for siemens step7, what plc are you using.