Event-driven DAQ

[Marcel Jahn]

I want to take readings from a DAQ - Card and if one of these readings
is out of pre-defined limits, I want to store the data in a file. I
hope somebody can help me.

Thanks.

Marcel

[John Rich]

It is not entirely clear what you are trying to do, but it appears that you should be able to perform this task by comparing the data points to the limits and then "and"ing the array to see if any one of the values is out of specifications.

A little more information would be helpful for a better answer.

John

[Marcel_Jahn]

Thanks for your posting. What I am trying to do is reading values and if these values are higher than a pre-defined value, i need to store values. The problem is, I want to store all the values 1 min before and after the actual event. I think I need a buffer of 2 Minutes and when a event occured, I need to wait 1 Minute and copy the buffer to file. Than I should have 2 Minutes of recorded data.
I dont know if this is the best way doing this and I hope somebody can help me.

Thanks

Marcel

[John Rich]

It appears to me that you have the right approach. I assume that since you are posting in the LabVIEW General forum you are not using RT and cannot obtain real time accuracy in the measurements. If you need precise timing in the DAQ then you need to go to RT.

A simple approach would utilize two buffer arrays. When a reading is taken you make it the last component in the first array which represents the first minute of data and take away the first component. If the data point is higher than the predefined value then you should put data in the second buffer array which represents the second minute of data. The two arrays can then be combined to form the array for output to file.

It may also be possible to use a trigger on the DAQ card to
achieve the desired results. I've not used this function and would be interested in other input.

Hope this helps.

John

[Marcel Jahn]

Thanks. I tried to set up something like this, but I have some problems to
program this. Does anyone have any example files ?

Marcel


"John Rich" schrieb im Newsbeitrag
news:5065000000050000000A0B0100-1042324653000@exchange.ni.com...
> It appears to me that you have the right approach. I assume that
> since you are posting in the LabVIEW General forum you are not using
> RT and cannot obtain real time accuracy in the measurements. If you
> need precise timing in the DAQ then you need to go to RT.
>
> A simple approach would utilize two buffer arrays. When a reading is
> taken you make it the last component in the first array which
> represents the first minute of data and take away the first component.
> If the data po
int is higher than the predefined value then you should
> put data in the second buffer array which represents the second minute
> of data. The two arrays can then be combined to form the array for
> output to file.
>
> It may also be possible to use a trigger on the DAQ card to achieve
> the desired results. I've not used this function and would be
> interested in other input.
>
> Hope this helps.
>
> John

[John Rich]

It would be useful if you could provide a copy of the code that you're working on so that we can evaluate what you're trying to do and why the code is not working.