PWM / transistor output connections

[russedwards]

Hi

Can someone please shed some light on a problem for me?!

I am fairly new to visilogic / unitronics and I am trying to control a proportional valve with a PWM block linked to an output. I am insure if I have the valve connected to the correct terminals of my V570.

I have a V200-18-E3XB snap in board.

I have a 24vdc +ve connected to the common connector of the digital output connector block.

+ve terminal of the valve connected to O6

-ve terminal of valve connected to O0

I'm not sure that this is correct?

[Emil]

What is the interface of your valve? If it's proportional, I'll expect some kind of analog input on it. If so - how this is related ot PWM?

Having the proper information, I hope I'll be able to provide you with the right help.

[russedwards]

Hi Emil

The valve we are using is a burkert 2865

http://www.buerkert.com/COM/Products/MFC-MFM-LFC-LFM-and-proportional-valves/Proportional-valves/2865.html

We do not have the controller for this valve that converts a 4-20 signal to a pnp PWM control, we would like to link the valve directly to the V570 and use the pressure transmitter also linked to the V570 to control the valve.

[Emil]

Hi Russ,

It seems good idea to use V570 to drive the valve proportionally via PWM.

Some tips:

If you have Snap In module V200-18-E3XB, you must use one of the transistor outputs. It can be in PNP mode. You need ot use DO0 or DO1.

Wiring:

You need to supply first 24V DC for transistor DO - to pins V1 and 0V. Please see chapter "Wiring power supplies" in the beginnning of page 4 of the spec. You can find the spec in our site www.unitronics.com > Support page > Technical Library.

It seems you need to connect +Ve of the valve to O0 or O1 (see "Transistor outputs" chapter in page 5, follow PNP wiring diagram on left).

-Ve of the valve needs to be connectged to 0V of 24V power supply.

You must connect reverse diode to the valve. I recommend you 1N400x or even more powerful (1.5A or more).

Then, in Hardware configuration of your project, you need ot set High Speed Output (HSO). I recommend you to set constant frequency at 400 Hz and to change duty cycle from 0 to 1000. This way you will get the valve opening proportionally 0-100.0%.

Please let me know if you need further help.