Yongqing Ye

Has anyone here tried External Node?

What is the execution oder of the cases in External Node?

I found the "redraw" reply will also trigger the case "PropType", is that right?

Thanks!

I just encounter occaisional delays every now and then when writing data. This is a problem because my data acquisition buffer gets full during the delay and I loose data. Well, I made an enormous data acquisition buffer to overcome this problem. I also get LV to hang when I acquire data after about 30 mins, but I think the problem is no in storage VIs but rather on front panel buffer.

I use the HDF5 because it allows me to

• Write multidimensional arrays, storage VIs support only 1d arrays (maybe 2d)
  
• Create hierarchies of unlimited depth, storage VIs allow only two levels namely channel groups and channels
  
• Add any number of attributes and any type of attributes, storage VIs support only predefined attributes
  
• Write complex number arrays
  
• Read selections of the data instead of the whole data
  
• Write parts of the data instead of the whole data
  

Thank you, I see.

No, it is not implemented using storage VIs and storage VIs are not implemented using HDF5 (at least to my knowledge). The quotation below from HDF5 homepage tells propably more. See HDF5 homepage for more details.

The LabVIEW library I have written implements central parts of the HDF5 C library. It currently ony works on Windows.

Thank you, Jimi! :thumbup:

And I want to know is there any other disadvantages of Storage VIs except the performance? When I using them, especially "Write Data", they always cause LV hang, I have to kill the process of LV at last. Did you also meet such a situation? Thanks again!

Depends on your needs. Storage VIs are very easy to use. The performance is however a bit slow and undeterministic. I use them in a few projects because Diadem can open TDM files written by storage VIs. On more demanding projects I use HDF5 1.8 library of our own which performs better and more quite a lot more flexible but also more difficult to use. Unlike in TDM there are no limits to data dimensionality or file hierarchy depth or number of attributes. Anybody interested in becoming a beta tester for HDF5 library, please contact me.

Thanks!

You mentioned HDF5, what is it? and what's the relationship between Storage VIs and it? Is it implemented using Storage VIs? If so, I'd like to be your beta user:)

Has anyone here tried Storage VIs?

what do you think of Storage VIs in LV?

Thanks!

re

I am new here.