locked time axis

[MvdH]

Hi all,

Recently I have problems with a locked time axis. I can generate a time axis, and modify it, but after I save it, it is somehow readonly. The status can be changed to free without problems, but still I can not modify the channel then. Currently I just want to make it shorter to match a shorter data set, but other times I will add a given start date and time which also doesn't work. It shows calculation succesful in the status display of the calculator, but the data is unchanged. Also the background in the viewer is solid grey instead of white/grey.

Thanks,

Marcel

[Brad_Turpin]

Hi Marcel,

You've raised a number of topics here.  I assume by "time axis" that you are referring to a time channel which you created in ANALYSIS.  In earlier versions of DIAdem such time channels would always be created as explicit channels, but in the last few versions, I believe starting with DIAdem 9.1, the default is to create an "implicit" time channel.  The "implicit" time channel only stores the start value, the increment value, and the number of values, so it is highly efficient both in DIAdem memory and on disk when you save it to file, but you can not change the values of an "implicit" channel.  You can, however, convert an "implicit" channel to an "explicit" channel by right-clicking on it in the Data Portal and selecting "Expand Channel".  You can, though, arbitrarily change the length of the "implicit" channel as long as you don't need to also change the start value or the increment value.

How are you importing your data?  It seems to me that it would be best to create a DataPlugin which automatically added a time channel with the correct values, or perhaps even declared the data channels as waveforms.  If you have DIAdem 9.1 or later a DataPlugin would be an option, and with DIAdem 10.0 or later waveforms would be an option.

Ask if you have further questions,
Brad Turpin
DIAdem Product Support Engineer
National Instruments

[MvdH]

Hi Brad,

Thanks for the information. The expand channel option is just what I was looking for.

The problem was not related to the import of data however. I am combining a number of files in one larger file after they are filtered and reduced to a much lower sample rate for static analysis. This is done by creating a new file with a long time channel in which I copy/ paste the channels of the shorter reduced files. For convenience I always start at 01.01.0000 and just set it to 5 million records or so. Now of course if I do not have enough small files to fill 5 million records the autoscale report plot will look very strange and thus I need to cut the time channel. Further to that I may want to set the starting time for presentation issues and I will also change sampling interval slightly to adjust for differences in hardware and Windows time to make sure that starting and ending time are corrected to the computers system time. I could of course calculate this exactly when I start the script to combine the files, but very often I will just look at a number of these combined files and only present one that is interesting. Thus I only 'optimise' the ones that I need which normally saves me some time.
All in all pretty straight forward, but also very difficult if you cannot modify the time channel.

Thanks again,

Marcel

[Brad_Turpin]

Hi Marcel,

If you have DIAdem 10.0 or higher, and if the time values are equidistant, then I recommend using waveforms instead of a time channel.  You can directly edit the start time of waveform channels so that they display at a different starting X value.  In DIAdem 10.1 you can directly edit the start time of a bunch of waveform channels all at once with only one edit action in the Data Portal property window.  You can convert numeric channels to waveform channels after importing them, but it would be much more convenient to have the conversion happen as the data are imported.  In DIAdem 10.1 you can define custom loading actions, for example that numeric channels always convert to waveform channels.

What data format are your files in?  TDM?  DAT?  CSV?  With DIAdem 9.1 or later we might be able to handle the waveform conversion in a DataPlugin.  What version of DIAdem do you have currently?

Also, are you concatenating these channels together?  If you identify 5 files with 10 channels each of 100,000 values, do you end up with 10 channels of 500,000 values?  If so, I have an application that handles the time axis automatically and gives you a convenient multi-selection file dialog to pick the 5 files.

Regards,
Brad Turpin
DIAdem Product Support Engineer
National Instruments

[MvdH]

Hi Brad,

We recently updated to 10.1 and data is in DAT format originating from an IOtech Wavebook binary. We also have the data plugin for the Waveview raw binary files which isn't advertised anywhere on the IOtech or Diadem website, as it seems to be under development, but sometimes we use this to directly import data and it works fine as well.

I'll have to look into custom loading and waveform editing as I've never used it, but I'll give it a try. The concatenating function you're talking about could be very helpful as well but there is one other "trick" I sometimes perfom in my scripts. Since the digital low pass filtering shows some transient behaviour at the start of the file (even when using zero offset and phase correction) I sometimes cut the first 25 samples of the input file to avoid getting spikes in the concatenated signal. But if you have a link to the program I'm very interested as I do not always need to do this and that way I can of course save some time programming scripts.

Thanks,

Marcel

[Brad_Turpin]

Hi Marcel,

The link for this particular example got injured and hasn't been fixed yet, so I'll just send you the ZIP.

Brad Turpin
DIAdem Product Support Engineer
National Instruments