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Operation of the TDMS Write VI.

Does this VI append data to a file that currently has data or does it overwrite the current contents? What I would like to do is to create all the channels and property channels first and then add data later. Currently, the TDMS Write VI is used to create channels and/or add data, but if I use the VI to just create the channel, I must also wire the data input as it is a required input. This is fine, as long as I can then overwrite that data with the correct channel data later.
"All truths are easy to understand once they are discovered; the point is to discover them." -- Galileo Galilei

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Hello settlesj,

 

I am unsure of what behavior writing in the manner to a TDMS file will do, but you do not need to create your channels in this manner.  If the channels are not already in place when you are writing your data, it will automatically create them for you.  If you need the channel names to already be in place for some reason (I'd be curious to hear what the reason would be, I'm thinking maybe for a UI), you can place them by using the TDMS Set property VI.  Just create two empty constants for the required inputs.  The channel and group you specify will be created with no data in place.

ColeR
Field Engineer
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Both "TDMS Write" and "TDMS Set Properties" will automatically create groups and channels if they do not exist. You can first set up all your channels and their properties with "TDMS Set Properties" and then add data values to these channels by calling "TDMS Write" and passing in the same group/channel names.

 

Herbert

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