Controlling relay board via printer cable

[smercurio_fc]

Well, the question is a bit vague so I will have to provide a general answer. There's a number of ways to do this depending on what you're doing inside the loop that you want to run for a certain length of time. One simple way to do it is to use the Elapsed Time VI. The attached example shows how to blink one LED at one rate for 3 seconds, and then a second LED at a different rate for 3 seconds.

[gwilbob]

Do you think that you could save that as a LabVIEW 7.1, please?
thanks for the reply!

[smercurio_fc]

Here you go...

[gwilbob]

My program is progressing extremely well, and I'm learning a lot, but I've got stuck again:
If I have 3 different tasks each inside its own While Loop (as per the example kindly provided above), I'd like to run one and then the second and then third, but sometimes I'd like to miss out the second. I tried to make a control using two Boolean Ands in the style that your stairs lights are connected, but whatever I do it sends a signal out (true or false) which triggers both loops.
I want it to send on the signal received to one of the loops, and do nothing to the other.
This sounds awfully complicated to describe!
Can anybody help? I'd imagine that this is quite a quick fix if you have the knowledge...
thanks!
Gwilym

[smercurio_fc]

You may be getting to the point where you would want to use a state machine. It sounds like your logic is a little messed up. Please post your code if possible or at the very least a screenshot (in PNG format, not BMP).

[Ray.R]

It sounds like you need a State Machine architecture.

Do a search on "State Machine".  There are plenty of examples within this forum.

R

[gwilbob]

Code as requested. The selector.vi doesn't do what I want- all I need is like the example below, I think!

I would have each of the instances as separate subVIs, but since there are switches inside the loops LabVIEW says making them into subVIs will alter the functionality.

I'll look at State Machines now, thanks for the tipoff!

Message Edited by gwilbob on 08-13-2008 06:17 AM

[smercurio_fc]

Ummm... Your code is a mess. Really. Each of your loops appears to be identical. This means subVI. Since you want to have the loop stop from the front panel control you can pass a reference of the "Stop" button to the subVI so it can read its value. And I couldn't follow your Boolean logic at all.