retriggered AO with PCI-MIO-16E1

[Holger Hofmann]

Does anybody know how to achieve the following task with
a PCI-MIO-16E-1 board ?

Digital pulses with a fixed frequency in the range of about 20 to 50 Hz should
trigger
an Analog Output waveform generation. The output waveform should be a quasi
continuous sine wave (with a period equal to the trigger period),
where the sine starting phase can be choosen by front
panel control, and with every trigger the sine should start at the specified
phase.
If you do a continuous sine wave (or arbitrary wave) generation with one
start trigger, the phase of the sine will walk away with time since you will
never
be able to perfectly match update rate and buffer length etc. to the trigger
period.
There would be no problem if one sine
cycle finishes shortly (100 microseconds
or so)
before or after the trigger puls. But there must not be longer gaps in the
output
waveform, like you will find them when you wait for finishing one buffer
output and then
start the WF generation again.

Any suggestions ?

Thanks, Holger

[conichi]

Well, i guess i am looking for something similar.
The board is a pci 6115 and would like to trigger lots of single sine waves.

The point is, sometimes the trigger comes before the sine wave is finished, and sometimes afterwards.
For the afterwards trigger, it is possible to use one of the examples,(Gen Mult Volt Updates Int-Clk Dig-Start.vi) put it all in a while loop, and trigger shortly after the wave has finished.

But what if the trigger pulse comes before the wave has finished..the waves stop for a whole cycle.. thats to late.

How can i start the wave right away?

Regards
Cristian from Germany

[Ryan_V[DE]]

Cristian,

Just so that I understand you correctly, you want to trigger a new waveform even if the previous waveform is not yet complete? Unfortunately, there is no way to do this purely in hardware with your device. The closest you could get would be to use a digital signal as the timing source for a software timed loop. Upon this digital signal, you could update the analog output buffer with new data. There would, however, be some latency from the digital line, to the software handling the interrupt, to the software writing new data to the buffer, to that data actually making it through the buffer into the DAC. Would this non-instantaneous triggering be acceptable?

The other option would be to use a signal generator frequency list in burst trigger mode, where each digital edge initiates a new frequency output. Here is a link to our signal generator products. Please let me know a bit more about your application, and I would be more than happy to help you find the right generator for you.

Hope this helps,

[conichi]

Hello Ryan,

well thank you for answering. I will try to explain my idea/task.
There is a wave generator, (in this case the electricity from the power supply), that has not exactly 50Hz, sometimes faster, sometimes slower. In my example the wave has 0,5Hz.

I would like to couple/interlink this wave with another that i produce.
So i thought of generating single waves.
every wave is started by pressing a trigger (that i built with a battery and in the future will be an automatic trigger triggered itself by the electricity), and sometimes the trigger sends its pulse, so the wave begins, before it has ended. If it has ended, a new one will be created, but if it is not finished, the trigger is being ignored.

hmm, i know i am writing a bit confusing. i am a rookie in labview things and this task is driving me nuts.

Another point of view: I would like to create a continuos wave out of finite samples, triggering this finite samples every time. In case of delay of the trigger it will of course wait... but, if the trigger comes before, then it will look like as if the wave has no interruption..
hmm. i get another idea,.. if the triggering pulses are every time before the ending of the wave the frequency could be faster, so it adapts itself....

i will post my example, that is a variation from "Gen Mult Volt Updates Int-Clk Dig-Start.vi" just a loop around and error handlers. Please have a look, and tell me if i have to start all over or continue on this manner.

by the way, i did not unterstand what was meant with DAQmxCfgDigEdgeStartTrig() and
DAQmxSetStartTrigRetriggerable(). Seems to have to do with Borland.. right?

Thank you for reading and helping,
Regards from Germany, Hamburg
Cristian

[Ryan_V[DE]]

Cristian,

Do you want to simply phase align your output sinusoid with another? I'm not sure what you mean by couple/interlink. If that is the case, you could perform a software PLL with your analog input to align the output sinusoid with the other one. Basically, you would simultaneously sample your output (this can be done internally without feedback wires) as well as this AC power signal. You would then calculate the difference over a few periods of the waveform, and measure the highest frequency component of each. Then, you could adjust the frequency of your DAC (using a DAQmx property node) to phase align and match the frequency of your two signals. Would this be an option? If not, please elaborate on what you mean by couple/interlink.

Hope this helps,

[phuongvtp]

what can i do with board PCI MIO 16E1?.I need help as complete unit experiment.i wating everybody

[_kb]

Hi phuongvtp,

Are you trying to retrigger an AO task?

If not, your question is unrelated to this thread -- you'll be better served creating a new thread and including some detail about your experiment.  Tacking a post onto the end of an old thread makes it difficult for other forum users to find information, and your questions won't get as much visibility.

[phuongvtp]

I want  trigger pulse PWM  control motor DC.But I don't know the method implement with PCI-MIO-16E1?.Can you help me?