Delay the operation of one button after another is released?

[Plasmaticon]

I have two valves that take about seven seconds to close after releasing the FP button. I have each button already disabled when the other is active, but I also need to keep each button disabled for approximately 7 seconds after the other button is released. Is there an easy method to do this?

[sergesl]

Hello Plasmaticon

I will need to have more information about your system. What is FP button? are pushing virtual buttons on the computer using LabVIEW or do you have real button? Please provide more information and we will be able to give you some suggestions.

Serges Lemo
Applications Engineer
National Instruments

[Plasmaticon]

Serges,

Thanks for the reply. The button that is being pushed is a virtual one for a front panel controller. I figured out a way to do it using an event structure, but it is very tedious since we are programming in DeviceNet.

The basic Labview function can be described by the following: There are two toggle switches. When toggle 1 is turned on, toggle 2 must be disabled. That part is easy. As soon as toggle 1 is switched to false, toggle 2 must remain disabled for 7 seconds. The problem I encountered using the event structure was that when toggle 1 goes from true to false it immediately enters the event structure without actuating the physical valve on the tool that we are controlling until after the event structure completes. It enters the 7 second delay for toggle 2 while toggle 1 remains in the true state. I was able to overcome this problem by creating a sequence in the event structure that writes each output to the tool in the first frame. The problem with DeviceNet is that you have multiple signals transmitted to various devices in bit-level format. So, I have write the current signal for every device connected to that pneumatic actuator. Since I have to do this type of logic for multiple switches, it is going to create a large messy VI. It seems that there could be an easier way to accomplish this task?

Thanks again for the help.

[sergesl]

Hello Plasmaticon

If i understand well, you are trying to synchronize different parts of your programs, but would rather use a different tool other than event structures. LabVIEW has many different ways to perform synchronization. Two that can be very useful in your case are Notifiers and Semaphores. I have below a few links that will help you understand what they are and how to use them and provide you with examples:

- http://digital.ni.com/public.nsf/websearch/B9398355D9550EAF862566F20009DE19?OpenDocument

- http://venus.ni.com/stage/we/niepd_web_display.DISPLAY_EPD4?p_answer=&p_guid=B45EACE3D81D56A4E034080020E74861&p_node=DZ52071&p_rank=&p_source=Internal&p_submitted=N

- http://venus.ni.com/stage/we/niepd_web_display.DISPLAY_EPD4?p_answer=&p_guid=B500C6E7AB0422E1E034080020E74861&p_node=DZ52071&p_rank=&p_source=Internal&p_submitted=N

- http://venus.ni.com/stage/we/niepd_web_display.DISPLAY_EPD4?p_answer=&p_guid=B45EACE3E6B556A4E034080020E74861&p_node=DZ52071&p_rank=&p_source=Internal&p_submitted=N

I would advise you to try and use Notifiers for your application and contact me if you need further help with this issue.

Serges Lemo
Applications Engineer
National Instruments