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Issues with NIFGEN_VAL_STEPPED
QDoe
Member
07-14-2015 06:49 AM - edited 07-14-2015 06:52 AM
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Hi,
I had some issues lately using niFgen_ConfigureTriggerMode with NIFGEN_VAL_STEPPED. I have a digital signal, every 300 ms, running on a separate board. I use this signal to trigger my niFgen board to emit a signal at 7100000 MHz during 1 ms and then 7164000 during 1 ms and then again 7100000 MHz,... . I create a frequence list and I configure it to be at 4V, phase = 0.
Everything works fine except that when I look at my picoscope, fixed on the 300 ms digital signal, the emitted signal starting point is randomly changing by an amplitude of 3 micro seconds, like if the way the trigger is seen by PFI1 was slightly changing for each repetition.
The funny thing is, if I restart the task between each digital signal(AbortGeneration then InitGeneration), timings are rock solid. I could live with that except that I would like to change my 300ms repetition time to 15ms repetition time or lower and restarting the board is going to take too long.
So here is my question : Why a constant trigger doesn't result in a constant signal starting point in NIFGEN_VAL_STEPPED mode?
Many thanks,
07-15-2015 10:02 AM - edited 07-15-2015 10:03 AM
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Just maybe to make it more clear and reproductible :
Using the FGEN Soft Front Panel, I used a frequency list generation of standard function mode, with a sine pattern, with PFI1 source trigger, in stepped mode, with a frequency list with just one stage (7MHz, 1ms). I send a digital signal every second or every 500 ms, and I run that.
The delay between the generated signal and the trigger is changing at each iterationbeing shorter or longer from 1 or 2 microseconds, randomnly. Is my card broken or is it a normal behavior ?
Sorry for the double post.
Louis.L
NI Employee (retired)
08-06-2015 10:00 AM
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Hi QDoe,
Do you still have your issue with the accuracy of your trigger ?
If so, can you provide your code and I'll try to reproduce the situation.
What is your exact hardware configuration (reference of your NI card/trigger source) ?
Best regards
Louis
Louis
National Instruments France
08-10-2015 04:53 AM
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Hi Louis,
Thanks for your message. Unfortunately, I still have issues with the accuracy. The code I'm using is written by National Instruments as I'm using the software which is bundled with the niFgen drivers. I don't have access to it but you don't need it to reproduce the situation. Just use the FGEN Soft Front Panel (software located in National Instruments/NI-FGEN if you have drivers installed) in stepped mode. My hardware is :
- PCI-5402
- Trigger generated by an Agilent oscilloscope, every 200 ms, 1 ms width, 5 V (MSO-X 2004A)
Let me know if you need further details and if you observe the same issue.
Regards
