Start recording data at a steady gradient (myRIO)

[BBrown105]

Currently I am measuring a single stream of data which eventually reaches a relatively constant zero gradient, and what I want to do is record the data for say 30 seconds once it reaches a relatively flat gradient. Another thing is that with each test the value the gradient reaches is different so I cant just say once it reaches x start recording I have to monitor the signal on once it reaches close to 0 I beign recording.

If anyone can help that would be greatly appreciated.

Thanks

[Tom-S]

Hi,

I have really quickly put together a quick VI that shows how you can use the 'In the range?' function and Elapsed time express VI to determine whether a signal has been stable for a certain length of time. In my example by time to check stability is 5 seconds and I have used +- 10% of the signal to determine whether it is stable.

Hope this helps,

Tom

[Corey.Rotunno]

I would acquire the signal continuously and feed the data into the dx/dt VI and look at the output of that to get close to 0. This will require filtering to get a smooth dx/dt (velocity), otherwise it will have many peaks and probably cross the zero threshold many times.