10-31-2014 09:55 AM - edited 10-31-2014 10:21 AM
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
11-03-2014 02:42 PM
Could you please provide some screenshots of your current configuration in SignalExpress?
-Devon
11-04-2014 08:53 AM
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
11-04-2014 09:02 AM
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
11-05-2014 02:45 PM
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
11-05-2014 03:35 PM
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
11-06-2014 02:40 PM
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
11-07-2014 09:55 AM
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
11-10-2014 06:48 PM
Hi GYepes,
Are you actually wanting to use a start trigger? I see you've got one set for a rising slope.
11-12-2014 09:12 AM
Hi Rick,
Yes and I am open to any alternatives suggested. My questions at the top of my initial post remain.
GYepes