Voltage monitoring for zero?

[wepsiec]

Hi. I need a way to monitor a signal for a six hour period to ensure that the signal does not fail. I assume I need to monitor the voltage for a prolonged zero reading. I also am supposed to rig this so if the system fails to function (e.g. no signal for a certain period) an alert will appear notifying the researcher that the signal died and for how long. The system is a white noise generator. Any ideas? I've attached my VI as well.

[ShishKeBobby]

Hi Wepsiec,

You can make a parallel loop where you pass the current signal value over via a local variable.  Using a case structure you can start a timer which compares the current time to the last known good signal time.  The difference is your time of connection loss.

[wepsiec]

Thanks. However, I am not sure what you mean by passing the signal over via a local variable. I can make a timer with a case structure, but because the signal varies above and below zero, I'm getting an error everytime the signal fluctuates. I used a one button dialog funtion to display the error, but I think I need something other than a simple more than/less than comparison. Does that make sense?

[apok]

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@wepsiec wrote:

Hi. I need a way to monitor a signal for a six hour period to ensure that the signal does not fail. I assume I need to monitor the voltage for a prolonged zero reading. I also am supposed to rig this so if the system fails to function (e.g. no signal for a certain period) an alert will appear notifying the researcher that the signal died and for how long. The system is a white noise generator. Any ideas? I've attached my VI as well.

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assumming that the signal swings above/below zero, but you want to capture zero for a certain period set by the user...after that condition is met, flag the user with an alarm?

hopes this helps, its simulates the zero crossing of the signal depending on the pressed "zero" button. the VI will latch alarm indicator once the preset time condition is met...

Spoiler

[crossrulz]

Apok,

Why the separate loop with the event structure?  Just put the buttons in the main loop and call it a day (use a latch mechanical action on the stop button).

[apok]

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@crossrulz wrote:

Apok,

Why the separate loop with the event structure?  Just put the buttons in the main loop and call it a day (use a latch mechanical action on the stop button).

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just trying to follow the previous suggestion with a local, plus trying to second guess the OP...if i sat down and thought about it more, obviously it would look different