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Sample rate query

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Sample rate query

Postby Jamie » Tue Aug 23, 2005 4:13 pm


We have recently bought a 3204 with Picolog to perform some simple data capture (load in Newtons against displacement in mm, using a load cell and linear transducer).

When capturing data I know it is possible to sample in realtime at a very high rate, but when viewing the spreadsheet or x/y plot of the recording afterwards it seems that although data is captured at the rate i have set (for example 10ms) the resolution is very low, i.e. when applying load the gap between captured data is consistently around 3N (load range during the test is 0 - 50N, applied slowly by hand). Changing the sample rate does not improve this. Is this just something conected with the 3204 (non-adjustable capture rate at the BNC connectors maybe?) or am i doing something wrong with Picolog? I seem to only be able to pick up the same 15 load figures every time, e.g. 1.24N, 4.75N, 7.88N, never anything in between. Is there anyway of increasing the resolution - if thats the right term for it?

Apologies for the drawn out question.

Best Regards,

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Joined: Tue Aug 23, 2005 3:22 pm

Postby Sarah » Thu Aug 25, 2005 9:56 am


Thank you for your post.

Do you mean a vertical resolution? This for the 3204 is 8 bits. I am not aware of any way to increase this in Picolog. If the jumps in values you are seeing are too big then it could be a different issue. You need to make sure you are using as much as the voltage input range as possible - this will increase the resolution over the input. An 8 bit resolution should provide you with 256 points on the vertical axis over the whole range; does this seem right to what you are seeing?

Best Regards

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