Activate Switch

[harisskriss85]

Hi,

         I have a signal being read, I should activate another process if there is no difference in the value from the  last 100 measurements from the signal (say around 1% deviation). Can anyone help.

Best Regards

Hari krishna

[Blokk · Accepted solution]

You should attach your VI so we can see what you tried so far...

Do not expect that someone will give you a ready made solution here, make some effort in order to get help.

edit:

1. If you are beginner in LV you should start to go through the tutorials (online links you can see at the top right of the forum website).
2. There are point by point VIs, so you could use the "Standard Deviation PtByPt.vi" for example, with a buffer size of 100.

[m-ad · Accepted solution]

Idea: Use a VI with an Uninitiliazied Shift Register (USG) to store the last 100 measurements in an array that is saved in the USG between calls. Have a counter i in the VI that increases with every call (also saved in an USR). It is called each time a new value is generated. That value replaces the i%100 (modulo) -th element in the array. Once you have at least 100 measurements (i>100), you take the Mean of that array every time. There's a VI for that that gives you the standard deviation too. You can then compare it to your threshold value and output e.g. boolean which you can use to activate your other prcess in a case structure.

[Blokk]

Why to reinvent the wheel with additional shift register? We have the point by point VIs, they are very useful...

[m-ad]

One of my problems with LabView is that you have all these great built-in VIs but to know when you have to find your own solution and when there's a built-in one needs some experience. ^^

[Blokk]

Not this subVI, he should use the "Standard Deviation PtByPt.vi".

[altenbach]

Do you have problems analyzing the last 100 measurements (as everybody here seems to think) or with activating a switch (whatever that means).

Why do you only mention the switch in the subject if the question is not about it?

Please clarify what you actually need. Thanks! 

[harisskriss85]

Hi Blokk,

          Thanks, I was looking for option like this. Standard deviation Pt by Pt.vi solves my purpose. 

[harisskriss85]

Hi Altenbach,

       I was confused in choosing subject, my mistake apalogies. Thanks

[harisskriss85]

Hi m-ad,

         Thanks for your inputs, will work on this to for my understanding