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how can i generate a PWM with 5402

Hi,
 
I want to use 3 5402 fgen to generate Pulse Width Modulation signals. They have to be synchronized and the pulse width range should be larger then the standard 20-80 duty cycle.
 
I know that I can make a user defined waveform that can have a duty cycle outside of the standard range but then I have to resynchronize after any change of the waveform (any change of the PWM)
Is there a way to work around this with the 5402's that I have ?
 
thanks a lot for your help
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Message 1 of 4
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Hello PBAN,

I don't see a solution for this with the cards that you are using at this point.
As you said there is the 20%-80% limit when you are using the standard functions and if you use the user-defined function you will always lose synchronisation when you update the function.

Is your PWM signal by any chance TTL compatible? In this case you can reach what you want by using a counter.


Kind Regards,
Wouter
National Instruments
Applications Engineering
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Hey again PBAN,

Allow me to be a bit more precise.
You will not lose synchronisation everytime you load a new user-defined function, your output however will be 0 for some time.

When you start the generation synchronised, the counter on the numerically controlled oscillator on the board is running and is synchronised with the other boards.
If you at that point choose to download a new user defined function to the board, the output of the board will be zero while you are downloading but the counter at that point keeps on running, so you will not lose synchronisation with the other boards.
After the load of the new function has finished, the board starts outputting again still synchronised with the other ones since the counter never stopped.

So what you want to do is possible (what synchronisation is concerned) but only if you can live with the time the output goes to 0 every time you change the user-defined function.

Keep in mind that this would not be the case if you choose to output a standard function and stay between the 20%-80% duty cycle limits.

Kind Regards,
Wouter
National Instruments
Applications Engineering


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Hi Wouter
 
first of all thank you for your reply
 
I'm new with the synchronization so I was wondering how I could upload to the boards without stopping them first
Is there a special command to upload the user defined function during operation
 
I will try all ready a bit
 
It's not a problem for me if I have a short time of 0 output because I can't live with only duty cycle of 20 to 80 %
 
regards
 
Pascal
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