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3 Second Recording Segments

Hi!

 

I am a new user of Signal Express. I am looking for a method, using Signal Express, to record a 10 minutes signal into multiple, individually logged, 3 seconds-long sequential segments of the larger 10 minutes signal. As previously recommended, I have tried using the "recording options" to start recording (with "start conditions") at the beginning of my signal and using "stop conditions" to end my recording 3 seconds later.

 

My set-up includes using an NI cDAQ-9172 with an NI9215 module for data acquisition and a NI9263 module to output my stimulation signal to a S88K GRASS Stimulator.

 

Now my problem seems to stem from the "recording options": My signal recording has no problems repeatedly starting the recording at the right time; however, the "stop conditions" is what seems to be giving me trouble. If I set the duration of my signal to be recorded to 3 seconds, I get a 4 second recording. When the duration is set to 2 seconds of recording, I get my 3 second recordings! however with this I find that my, Signal Express, generated stimulation (that is sent to the S88K stimulator) is changed, becoming altered and of out of sync.

 

How / why would my recording options be effecting my generated stimulation? What might I be doing wrong in the recording options?

Is there an efficient way to achieve these sequential 3 seconds segment recordings of the larger recording?

 

I welcome and value any advice and ideas to these 3 questions!

 

Many thanks!

 

GYepes

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Message 1 of 12
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Could you please provide some screenshots of your current configuration in SignalExpress? 

 

-Devon

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Message 2 of 12
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Hi Devon,

 

I have attached a few screenshots of my setup. Please let me know if there is anything in particular that could be of help.

Thank you.

 

GYepes

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Message 3 of 12
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Also these attachments of my generated signal

Signal Generation 2: is the signal i'm generating to my stimulator

Signal Generation 3: is a trigger to get my stimulator to initiate the signal

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Message 4 of 12
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Can you please tell me exactly what you mean when you set the duration to 3 seconds?   How are you setting the duration?  I noticed in the screen shot the stop condition says > 3 seconds.  Can you change the stop condition to equals 3 seconds?  

 

Best Regards,

 

Devon R.

Applications Engineer

National Instruments

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Message 5 of 12
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Hi Devon,

 

I just mean that in the "condition type" box, I selected "duration" and set the "duration" to "3". I am assuming in this case that the stop conditon is equal to 3 seconds: once it has recorded for three seconds the recording stops and goes back to find the start conditions for the next recording. However as I've explained earlier, I don't find this to be true.

I hope this clears it up.

 

Regards,

 

GYepes

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Message 6 of 12
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The stop condition has a greater than sign in front of it.  If you are getting 1s worth of data each time, then it would makes sense that you get +1 seconds worth of data if your stop condition is set to be greater than x seconds.

 

Here is an example:

http://zone.ni.com/reference/en-XX/help/371268P-01/expresswb/example_temp2/

 

Stop-condition manual:

http://zone.ni.com/reference/en-XX/help/371268J-01/expresswb/stop_conditions/

 

Best Regards,

 

Devon R.

Applications Engineer

National Instruments

 

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Message 7 of 12
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Devon,

 

I agree with your observation, however I don't know how to change the > sign to have it stop at exactly 3 seconds? Any ideas?

 

Regards,

 

GYepes

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Message 8 of 12
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Hi GYepes,

Are you actually wanting to use a start trigger? I see you've got one set for a rising slope. 

Rick C.
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Message 9 of 12
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Hi Rick,

 

Yes and I am open to any alternatives suggested. My questions at the top of my initial post remain.

 

GYepes

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Message 10 of 12
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