Time delay

[stu22]

Hi, just a simple, but never any use for untill now. Basically a sequence to have a voltage on for 20 seconds,then time out and switch back to zero voltage. It also needs to be controled by the use of a case structure e.g.on/off.

Thanks Stuart

[Eric Forton]

Hello,

Here's a simple loop that perform your delay each time you push the start button.

You have to add in the diagram the commands that set your voltage on and off.

[stu22]

Hi Eric,

If possible canu put it in labview 6.02 as that what i'am using.

Thanks Stuart

[Anonymous]

Stuart,

I'm confused are you asking advice on how to toggle a voltage value on a
programmable power supply for a predetermined amount of time? If this is
true and you want the simplest answer, use a state machine. This is a
while loop with a case statement inside. Without going into elaborate
details, the while loop is constantly checking on the state of a user
input (could be boolean switch). Depending on the state during that
iteration the case will be set to the appropriate value.

In your case, you could have a blank case for when the user hasn't
pressed anything while the other case will have your voltage control
sequence (turn output OFF, set voltage, turn output ON, wait 20 seconds,
turn output OFF, set voltage to zero). (you may want to conside
r the
myriad of ways to break that 20 second delay if the user needs to)

Clue me in if my reply was has nothing to do with what you were asking.

- Kevin

In article <506500000008000000DD5A0000-1027480788000@exchange.ni.com>,
"stu22" wrote:

> Hi, just a simple, but never any use for untill now. Basically a
> sequence to have a voltage on for 20 seconds,then time out and switch
> back to zero voltage. It also needs to be controled by the use of a case
> structure e.g.on/off.
>
> Thanks Stuart

[Eric Forton]

here it is.

In fact, what I've done is axactly what the other answer tells you to do...

Bye.

[stu22]

Hi, i had the same idea , but for some reason when u wire the final sequence up so that the output voltage returns to zero it says "u have connected a constant to a an output sequence tunnel". Any ideas on how to get around this.

Thanks Stuart

[stu22]

Hi, yes thats exactly what i mean, but for some reason when u wire the final sequence up so that the output voltage returns to zero it says "u have connected a constant to a an output sequence tunnel". Any ideas on how to get around this.

Thanks Stuart"

[Eric Forton]

can you send me your file?

[stu22]

Hi, heres part of the main program i'am developing. All it is a control which controls an injection valve. so basically when the button is pressed on the front panel the valve will open for 20 seconds then close. It uses field point and labview 6.02, but if u can not use it just have a look at the case loop with the sequence in it. And the field point vi's should work that are attached.

Thanks stuart

[Greg_McKaskle2]

> Hi, yes thats exactly what i mean, but for some reason when u wire the
> final sequence up so that the output voltage returns to zero it says
> "u have connected a constant to a an output sequence tunnel". Any
> ideas on how to get around this.
>

The short answer is that you have connected two outputs together. The
constant produces data, and the output tunnel of the sequence produces
data, so if these are wired together, it will produce the error that you
are seeing.

I think what you are wanting to do is after the sequence, call the VI
again to set the DAQ output to zero. Just think of it as each time you
call the function passing in a value it changes the voltage on the line.

Greg McKaskle