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Q: Appending wfm to memory?

Question asked by yshin on Jan 25, 2011
Latest reply on Jan 27, 2011 by algoss

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HI,

What I want to have is similar to segmented mode acquisition but manually; acquire a waveform and append it to scope's memory.
It seems that ":WMEMory<N>:SAVE" simply overwrites the memory with the current waveform.
Do someone knows how to append current waveform to previous ones if it is possible?
I could use segmented mode but I need to control each trigger instead of getting some given # of triggers blindly(?).

Best regards,
Yun-Ha

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algoss Jan 26, 2011 7:05 AM
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What you want to do is not possible, the way you want to do it.

I don't understand why you can't use Segmented Memory mode. That mode allows you to control how may segments (triggers) you capture, and how deep each one is. They are time-correlated, and you can play them back.

Please describe what you are trying to do, and we can see if there's a solution.

AG
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yshin Jan 26, 2011 6:29 PM
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Thank you for your reply.

I have two different detectors. One of them has attached readout electronics and software but the other has no so that I'm using DSO9404A to readout the signal for it. What matters is to synchronize the triggers to the detectors. I tested the system with a source which gives triggers in about 4 kHz rate, and found some of them are missed in first detector. The scope was in segmented mode. Then I set a simple trigger logic with delay and gate generator in latch mode which is reset after read out the waveform. I used viWaitEvent for SRQ from single acquisition done event then read the waveform. The rate dropped to about 20 Hz. I thought it might help if I could save/append the waveform to the memory for some number of triggers and read them at once.

Regards,
Yun-Ha
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algoss Jan 27, 2011 8:21 AM
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You don't say how many scope samples you want to capture on each trigger, but the reset time in segmented mode is less than 25 usec, so with short acquisitions, you can run segmented at about a 40KHz rate. The rest time is from the end of the acquisition, so you'll need to consider how much time each acquisition takes, and add the reset time to calculate the segmented rate. The scope samples at 10GSa/sec, so if you take 1K samples per trigger, then the time between triggers is less than 25usec + 100nsec.

Your mileage may vary...

The 20 Hz rate for individual captures is about right.

AG
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Q: Appending wfm to memory?

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