Multifunction DAQ

cancel
Showing results for 
Search instead for 
Did you mean: 

Output a waveform with PCI-6713(problem)

Highlighted
I want to generate a waveform which contains a
a pulse of 0.01ms and another pulse of 10 minutes using one chanel analog output:
____ _______________
__ ________ __________
<--> <------------->
0.01ms 10minutes

in this condition,the buffer size may be too large! Any suggestion? Thanx......
0 Kudos
Message 1 of 3
(1,209 Views)
Highlighted
In order to produce this waveform using Analog Output with the 6713, you would need about 60 mega-samples to define the waveform at an update rate of about 100 kHz. I can definitely see how such a large buffer would be a problem!

National Instruments has some Arbituary Waveform Generators that provide onboard memory for waveforms, but the largest onboard memory currently available for analog output is 16 MB.

If the pulses you need to produce are for TTL compatible signals, then you might consider using the 6713's counters instead. You can program a counter to use Frequency Shift Keying. Basically you can specify characteristics for two different pulse trains. Then, depending on the state of the counter's gate signal, it will switch between one pulse train or an
other.

Controlling your gate signal may be tricky. You could use the other counter's output to generate a digital pulse that will be just long enough to produce the first part of your signal and then use software timing to count down 10 minutes for the second part. After 10 minutes, you could end your pulse train generation by resetting your counter. Just one idea, maybe this will get you thinking of other possible solutions using counters instead of analog output.
0 Kudos
Message 2 of 3
(1,208 Views)
Highlighted
Another possiblity is to use circular buffering for your analog output. Then you can divide your datapoints into smaller chunks and update the data buffer continuously as you go.
0 Kudos
Message 3 of 3
(1,208 Views)