I program my own system and have a question which I hope someone can help with.

I have a relay operating a swimming pool valve. When I open this valve I want to set a flag high I. If the button gets pressed again I want to check to see if the valve is already open. Can anyone please help with on how to do this and what symbols to use.

Many thanks

Is the relay held open or just need to be pulsed? You basically want to create a toggle based on feedback?

What processor?

Can easily be done with a buffer and a not symbol.

I have two relays, one is being pulsed, this slightly opens a valve to water feature and the other is held open with a toggle, this is power for the pump.

I am using a 2 series processor.

Any other guidance would be much appreciated.

For the one that is pulsed, can you pulse it multiple times to adjust the amount of water that is able to flow through the valve, or is it a pulse to open and pulse to close?

The other one is easy and just send the output of your toggle to the feedback of your interface.

The relay that is pulsed can be pulsed multiple times to adjust the amount of water.

I am hoping someone might be able to send a couple of screen shots with an example of how to get this to work.

Many thanks...

For the one that is pulsed is there a second relay to close the valve?

Can you provide a bit more detail how this waterfall relay is working? That will help with trying to come up with a solution for this.

I would use max 5 presets for the waterfall (0%, 25%, 50%, 75%, 100% water flow) From there you will have 5 buttons on your interface (Off, 25%, 50%, 75%, 100%) Using an interlock for your button press the output of the interlock will go into a truth table. You will need to have a second set of inputs and these come from the current position of your valve which will also come from an interlock.

Within the Truth table you will need to compare each possible option and on the output you will need to connect them to a one shot for each possibility. You will also need 5 Or's, one for each preset. Your output of the Or goes into the input of your second interlock (the one being used for current valve position).

Thank you SWOInstaller.

Yes, there is a second relay to close the valve.

At present I have an on button, this activates a stepper that pulses the open valve relay for 3 seconds to open the valve. Once the valve is opened another relay is set to high to turn on the pump. What has happened due to my basic programming skills is that if the on button is pressed again by mistake it is opening the valve for another 3 seconds but then turning the pump off.

Ideally what I want to happen is if the on button is pressed again by mistake to check to see if the valve is already open and the pump is running before the button press gets to the stepper.

I hope this makes sense.

Thanks again

[Link: i.imgur.com]; - A VERY basic implementation.  The off logic will trigger at system startup btw.  (out* evaluates high at startup.)

From what I have gathered from mullsey, he has both an ON and OFF button on his interface and doesn't want the logic to run if someone accidently hits the button a second time. For this he would want to use a SR (to hold the pump relay ON) but to also feed the Enable of two buffers which would stop that second button press from happening. He can also send the outputs of the latch to the feedback on his buttons to know the current status of the system.

Your logic does work if he only has one button for ON and OFF but in this case I don't think he has that.

For what Mullsey has provided I think that this will work better for him.

Thanks, you're correct.