motor valve control

[wew044]

Hello labview experts,

I am trying to put together a VI that does the following:

1. pressure setpoint respond to motor speed and valve.

2. motor and valve can be auto or manual mode.

3. pressure setpoint to motor is feedback, and pressure setpoint is feedforward to valve (not sure if this is necessary)

4. valve (proportional) is open at 100 and close at 0. 

Could you help with some of issues i am having?

1. i am not sure if the feedforward loop is done correctly

2, my valve is having trouble responding. It stays at 0 because that will increase the pressure while motor speed increases. (maybe having it ramp down from 100 would be a better idea but i am not sure how to implement that)

Please see attached file. i also attached a subvi that I created just to have some pressure output.

Thanks!

[herringbone]

Can you explain how the valve isn't responding? I ran the code on my end, and the valve responded almost instantly once I edited the Psetpoint

[wew044]

Hi Herring,

I think when you tested it, you did not set the P constant to negative. I set it to negative because I want the valve to open to decrease pressure and close to increase pressure increase. and that is what the simulator subvi does. So what happen is your valve knob probably jumped to 100 to match the pressure i think?

If you set it to negative, it will just stay at 0. and that is not what I want, realistically.

Thanks!