where is scalar rms in diadem?

[Jim_in_Oceanside]

All I find for RMS in diadem is "floating". Where is a scalar RMS?

[Jason F.]

Hi Jim,

A better place to post this particular question would be in the DIAdem forum here:

http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RPAGEID=8&RFORMNUMBER=3&RHIDETAG=TRUE&UCATEGORY_0=_317&UCATEGORY_S=0

To answer your question though I think we might need a little more detail as to what type of RMS calculation you are wanting to make, meaning that I'm not quite sure what you mean by "scalar RMS". Are you asking how to calculate the RMS value of a channel on a point by point basis? An exact description of what you are looking for would be greatly appreciated.

Jason F.
Applications Engineer
National Instruments
www.ni.com/ask

[Jim_in_Oceanside]

The wrong forum issue has happened before. Somehow when I have generated a question in the correct forum, after you pass through the layer of possible prior answers, the forum gets changed. Oh, well.
RMS. In labview the RMS vi takes in a 1D array and outputs a single, scalar RMS value. In diadem, you select a channel (in essence a 1D array), tweak a factor, and the calc result is another 1D array, not a single scalar value. I found if I set the factor to 100%, all (most) of the 1D result values are the same. Maybe that is my scalar RMS.

[Jason F.]

Thanks for the clarification, that cleared up everything. If you want to calculate an RMS value like the one that LV's RMS.vi does you can use Diadem's basic math functions to process your channel data to calculate that value. To do this, do the following:

1) Square all of the individual channel values
2) Add all of the squared values together
3) Divide the result by the number of values
4) Take the square root of that

This is the same formula LV uses, there just isn't a single function in Diadem that does it all in one shot unless you want to use the floating rms version.

Jason F.
Applications Engineer
National Instruments
www.ni.com/ask