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TDMS graph X-axis as time


In order to collect data for a fluorescent experiment, I need to extract only the data when the pulse(red) goes off. In this case I would like to collect only the data in the segment of 2 green lines; i.e. once the pulse goes OFF.

  1. What's the axis units of TDMS file, although it looks like in seconds, the entire acquisition time completes within 4ms. So this looks wrong.
  2. The reference position for fetching the records is set at 0.0%. Which means the moment the digitizer sees a trigger it starts ignoring all pre-triggered data. How do I get the exact position (in terms of record number) of when the pulse(red) starts and stops. This will help me to select only the required recorded samples from the entire record length.

Pulse(red) and data(white)Pulse(red) and data(white)


NI System Configuration:
- NI PXIe-1071, 4-Slot 3U PXI Express Chassis , 1 GB/Slot throughput, Part Number: 781368-01
- NI PXIe-PCIe8381,x8 Gen2 MXI-Express for PXI Express Interface,3m, Part Number: 782522-01
- PXIe-5160 PXI Oscilloscope, 500 MHz, 10 bits, 2.5 GS/s, 2 Channels, 64 MB, Part Number: 782621-01
- Astronics PXIe-1209 2-Channel, 100 MHz PXI Pulse Generator, Part Number: 785033-01
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The simple TDMS viewer isn't always the best viewer.  It is quite limited and things like graph settings can't always be changed.  In this case I think you can right click and change a few things but I don't have access to it right now.  You can try an improved viewer called Scout X which is free (has a pro version). The graph functions are more customization and you may have more luck.  If that doesn't work for you, you can read the TDMS file yourself with LabVIEW or some TDMS DLLs NI has published to get the raw data that you can then operate on.

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You can change the time format Use "<$S$.6u>t"

"Should be" isn't "Is" -Jay
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