ritesh024

I tried storing data as BLOBS in sqlite and I found no difference in speed in retrieving data. I tried storing each waveform in a separate tdms file and retrieving data from it is much faster than sqlite(100ms in tdms compared to 400ms in sqlite) but still 5 times slower than action engines(20ms). I don't think that's acceptable as well.

Initially, I decided to use TDMS for storing waveforms but TDMS isn't a great choice if the user needs the ability to overwrite or delete the data. My application requires a lot of overwriting of data. There are ways to delete/overwrite data in TDMS but that requires creating a new TDMS file with new contents. As the data in my application can go beyond 100 MBs, creating a new file of that size takes a long time. I have not used BLOBs using your library. Do you have any example of how to use BLOBs. I tried searching online but couldn't find anything. maybe blob retrievals are faster than text. and I don't need to query anything on the measurement data itself so I don't think sqlite is a bad choice at all. Each measurement is associated with a unique id so I query the data using this id and it works great. my only issue with sqlite right now is that it takes a long time to return measurement data.

Hi James, Thanks a lot for this library. This is wonderful. I am using sqlite to store the measurement data. My data is 1D DBL and each waveform is about 5s @ 48k sampling rate so that makes the size of each waveform to be ~2MB. I flatten the data to string and replace any special chars(like NULL and ') and save the data as TEXT. All that is fine but if I want to retrieve say 10 waveforms, it takes about 350-400 ms to return the data which is not acceptable as the code will be used on a production line and time is a very critical factor over there. Also if I use action engines to store the waveforms then retrieving 10 waveforms only takes about 20ms on the same machine. I don't want to use action engines because the amount of data to store is going to be huge and thats why I am inclined to use sqlite. Is it normal for sqlite to take about 400ms to retrieve 20MB of data? Thanks, Ritesh

I haven't done much of OO programming in LabVIEW before but it seems like this could be a good starting point. Have you done any performance benchmarks on your OO code? How fast/slow is it in comparison to traditional cluster based solutions?

Hi All, I have an application where I store the data in a cluster. Suppose this is my ver. 1 of the application and the cluster consists of 3 I32. and I ship this application to the customer. Now for the ver 2 I want to store a string to the cluster so I updated my cluster to 3 I32 and 1 String. But this ver 2 should also be able to read ver 1. just like MS Word 2007 is able to read .doc files In my design, I am stroing the version number and data(as variant) in a cluster and convert that cluster to variant and do a 'variant to flattened string' before saving it to a file. I am attaching my desing protoype here so you get a better idea of what I am talking about and suggest me if you think it can be done in a better way. Thanks, Ritesh ClusterVersionControl_Design.vi

Hi all, I am trying to post my code in the code repository. Every time I click the submit button, I get a message saying that,"Screenshots are required, however you did not submit one", even though I attach a screen shot. I am attaching a .png file of 80 KBs. Am I missing something or is it some problem with the site? How can I resolve this problem? Thanks, Ritesh

Dear all, I am in a bit confusion in choosing between XY Graph and Waveform Graph to plot my data. Here is the Scenario: i am receiving data for 24 channels(400 samples each) from my H/W. so the X scale of the Graph is 0-399. Now once i have captured all the data, i might want to change the Sweep speed of a particular waveform. Sweep is like Zooming in or Zooming out. Say if i captured the data at sweep speed = 2. Now i want to view it at 4, means, i want to Zoom Out. Now that means that i want to view my 400 samples on First 200 samples of the Graph. If earlier the X difference b/w points was 1. not it'll be 0.5. Waveform Graph has the property wherein i can make a cluster of Initial X, delta x and the waveform. Problem is it'll take delta x for all the plots on the graph and wont work if i want to change delta x of just 1 plot. In XY Graph, i can give X and Y values for independent plots. So, it can workout my problem. But giving X and Y values is a bit tedious job. I want to know is there any way i can use Waveform Graph to plot my data and can change sweep speed of just 1 plot without doing much of coding, or is XY Graph the only solution to my Problem ?? Ritesh

I want to store "array of cluster" in TDMS file. First i wired the "array of cluster" wire to the Write TDMS Cluster_TDMS.vi, and it gave some error. Then i created a cluster of array of cluster and wired it to the Vi and it hung my Vi. How can i store array of cluster in tdms file ? Ritesh

Why can't i see Write TDMS Cluster_TDMS.vi in my OpenG package ?? I updated OpenG package around a month back. is it a recent launch ?? Ritesh

Thanks Minh Pham. You are inputting the values of offset and multiplier of the X-Axis to a cluster and then outputting the clustered value to a graph. That is not changing the scale of the Axis but the data only. Is it possible to send the 1D array of scaled data to the graph and not the Cluster of 3 elements? Actually, i have already completed 50% of the project and all time i am sending 1D array of data to the graph. not it would be really tough to change !D array of data to cluster of 3 elements. Thanks, Ritesh

Thanks Minh Pham. That is really a nice approach. After trying hard on NI forums, i got a solution which used "decimate 1D" array to get the desired result. And your solution looks really simple. Thanks, Ritesh

Dear all, I am working on an application where i am recieving data at 5 ms/Division and i am plotting it on Waveform Graph with X-Scale 0-100. Now, i want to show tha same data at 10 ms/D. i.e the whole data will be shown on 50 points now. PS: i dont want to change the scale of the Graph. X-Scale of the Graph will still be 0-100 . How can i do it in LV? Thanks, Ritesh