Use of multivarible case statements and delay between actions

[Zeprenize]

Hello. I need help programming my LabView Application. I am using it to control valves and read in from pressure gauges for a vacuum system.

I want to have one switch to check to make sure I am in a safe configuration and adjust the valves accordingly for experiments.

When I flip the switch I want check to make sure that both my pressure gauges are below a set value. If they are I want to close the second valve, wait two seconds, and open the first valve.

When I flip the switch off I want it to close the first valve, wait two seconds, and then open the second valve.

However, I also want to program itself to be able to run continuously until I tell it to stop so I can monitor the pressures from the computer even when not changing the system's configuration. Yet, when I try to implement a case statement in my program to deal with checking the two gauges, I end up in an infinite error loop since the switch is off.

Furthermore, I don't know how to properly implement a delay between two set actions and not just making the entire program function at the delayed rate.

I have gone through several online tutorials, but still they don't seem to help or answer my questions well enough to allow me to accomplish my task. More functionality is to be added later, but I know that if I can solve these few problems I will be able to deal with the rest since what will be added on later are just permutations of the same things I am having trouble with currently.

Thank you and any help you can offer will be greatly appreciated.

I have attached what I have for the program in question in case that may help.

[johnsold]

Your project is well suited to a state machine architecture. The pressure readings could run continuously in an independent loop and feed the data via a queue or LV2 style global. Your state machine could have one or more states in the "Safe Mode" and other states which open and close the valves at the appropriate times. Still other states might handle the automatic operation. Your description is not sufficiently detailed to allow me to be more specific. Check the examples and search the Forum archives for state machines.

I wondered why you have two sets of valve controls?

Lynn

[Zeprenize]

We have the vacuum chamber attached to an EUV source. EUV is extreme ultraviolet lithography and can only effectively pass through a vacuum. The source has it's own vacuum and our chamber another. If there is a leak in our chamber we don't want it to leak air into the source.

The first valve is glass and it divides the two vacuums, keeping them safe from leaks or contaminates. The second valve is a Zirconium foil that is very sensitive and only allows EUV light to pass through. If the pressures between the two vacuums are too disparate the foil may break. Also, switching both the valves at the same time can put the foil in danger of damage or contamination. That is why we want a time delay between the closing the foil and opening the glass, and vice versa.

Thank you for your suggestions and I will look into them next time I am in the lab.

With case statements about an hour after posting I was able to figure out a way to implement them correctly by nesting two case statements and changing the value of incoming loop after one iteration. I am at home now so it is more difficult to explain it, but overall the solution I have implemented now is a little convoluted so your solution may be a better solution.