acquisition duration vs trigger frequency

[Loic VINET]

I am using a python program in a raspberry connected to a digital Discovery.

I have a trigger every 1 second with a duration of 100 ms.

I want to make an acquisition of 20 ms or less.

The problem, I have, is that when running the function dwf.FDwfDigitalInStatus(hdwf, c_int(1), byref(sts)) give STS = 1, it stays in status armed and there is no acquisition.

When the acquisition has a duration of 1 s and more, it works.

What should I do to be able to have an acquisition of less than 1s acquisition duration?

[attila]

Hi @Loic VINET

Could you attach or send me the configuration or the entire script ?

[Loic VINET]

Hi @attila

Here is the python script. I include at the beginning the configuration.

The 1st one works (with 1s acquisition), but not the second one (with 0.1s acquisition)

Thank you for your help

scriptLV.py

[attila]

Hi @Loic VINET

The digital-in should be started before the digital-out, otherwise the out may finish or generate the trigger condition before the in starts looking for this.
Instead record you can use the simpler to use acqmodeSingle.

[Loic VINET]

Hi @attila

What do you mean?

I should place FDwfDigitalOutConfigure after FDwfDigitalInConfigure, that's it?

Do you have an example?

[Loic VINET]

Hi @attila

I place the dwf.FDwfDigitalOutConfigure(hdwf, c_int(1)) in the acquire function just after dwf.FDwfDigitalInConfigure(hdwf, c_int(0), c_int(1))

    dwf.FDwfDigitalInConfigure(hdwf, c_int(0), c_int(1))
    dwf.FDwfDigitalOutConfigure(hdwf, c_int(1))

But it makes no change.

if I replace acqmodeRecord by acqmodeSingle, it doesn't work in both cases.

The goal is to record signals with a trigger given by the PPS (pulse per second) of the GPS. This PPS is a square signal of 100 ms each second.

[Loic VINET]

Hi @attila

I found why it did not work.

The durationInSeconds in dwf.FDwfDigitalOutRunSet(hdwf, durationInSeconds) was too big.

It was 500, with 10 it works