Rising Edge

[ThomasD]

Hello,

does anybody have a simple solution for this problem?

Push-Button     LED

        0                 0

        1                 1

        0                 1

        1                 0 

        0                 0

With the first rising edge the LED should be switched on and with the next rising edge the LED should be switched of and so on. 

LV 6.0

Regards

ThomasD

[Norbert_B]

Thomas,

should that be in LV only or is there hardware involved? if only in LV: what is the mechanical action of the button?

Norbert B.
NI Germany

[ThomasD]

Hello Norbert,

hardware is only indirect involved. In the way with Push-Button and the LED I will do a previous check of the function in LV only. Later I will read in a signal from a pushbutton over the parallel port. The pushbutton which will be read in should work like a switch. Rising edge of the pushbutton --> "LED on" next rising edge of the pushbutton --> "LED off". I like to simulate this in LV.

[Norbert_B]

Thomas,

then you can do the following:
check the button (depends on architecture of your vi, use polling or event-based programming here)
compare with old status of button (shiftregister in while-loop)
if edge=rising
    toggle LED-status (shiftregister in while-loop)

this should work out quite easily for your needs.

Norbert B.
NI Germany

[devchander]

Hi Thomas,

look at attached VI

You looking for something like this?

Regards

Dev

[devchander]

Opps! did not observe you have LabVIEW 6.0

sorry, i do not have that version on any of my systems.

Sorry again for the goof up

regards

Dev

[ThomasD]

Hi Dev,

can you post a picture from the VI?

[Mark H]

Hi Thomas,

Here's how to do it with a very simple "XOR with previous value" method.

Note that it is important that the switch's "mechanical mode" is "latch when pressed" or it will not behave as you expect - experiment with the different "mechanical modes" and you will see.

I would have posted a lot sooner if I hadn't had to save all the way back to version 6.0 - time you upgraded perhaps?

Regards.

Mark H.

[devchander]

Hi Thomas,

Here is a Pic of the block diagram

In the shown block diagram, Click is a Boolean swithc with its mechanical action property set to 'latch when pressed'

and in the false state of the case structure, the boolean value from shift register is wired out

Regards

Dev