analog discovery 3 Define record time for Oscilloscope in Waveforms SDK

[gabagool]

Device: Analog Discovery 3

Hi,

I am wondering how I can increase the total recording time of the `scope` module in the SDK. I am trying to record and plot the output of a component and require a 30 second recording of scope data. 

Currently the SDK defaults to 0.5s.

What I am doing is:

def test(device_data):
    scope.open(device_data)

    dwf.FDwfAnalogInRecordLengthSet(hdwf, 30)
    dwf.FDwfAnalogInTriggerPositionSet(hdwf,c_double(-0.01))
    
    # set up triggering on scope channel 1
    # scope.trigger(device_data, enable=True, source=scope.trigger_source.analog, channel=1, level=3.3)

    sleep(1)    # wait 1 second

    # record data with the scopeon channel 1
    buffer = scope.record(device_data, channel=1)

    # limit displayed data size
    length = len(buffer)
    if length > 10000:
        length = 10000
    buffer = buffer[0:length]

    # generate buffer for time moments
    time = []
    for index in range(len(buffer)):
        time.append(index * 1e03 / scope.data.sampling_frequency)   # convert time to ms

    # Plot settings
    plt.grid(True)
    plt.yticks([i * 0.1 for i in range(0, 41)])
    plt.ylim(0, 4)
    plt.xlabel("time [ms]")
    plt.ylabel("voltage [V]")
    #Plot Data
    plt.plot(time, buffer)
    plt.show()

    scope.close(device_data)

 

SDK documentation and other forum examples showed the use of `FDwfAnalogInRecordLengthSet`, however this has not changed the time of recording. I also tried increasing the buffer size but no luck and removing the `if length > 10000` buffer check. What have I missed here? I found that setting `scope.trigger` waits until the threshold has been reached to start, but again this just records 0.5s worth of data when I need the full 30s.

Edited March 6 by gabagool

[attila]

Hi @gabagool

If you want to capture up to device buffer size see AnalogIn_Acquisition.py example and for more at lower rate use data streaming, see AnalogIn_Record.py or other similar examples.