remote program with python have a wrong data form RF input

[sophistGuapi]

I'm new of red pitaya develop.
I want to get data form red pitaya RF input,and compute them use python in my computer.At first I have program base on https://redpitaya.readthedocs.io/en/lat ... e-examples.I launch this example will endless loop in

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while 1:
    rp_s.tx_txt('ACQ:TRIG:FILL?')
    print(rp_s)
    if rp_s.rx_txt() == '1':
        break

so I delete these codes and run it succesful.
but when I loop the code to get data and update in plot,It just print first data with these codes:

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def get_source_data(device):
    device.tx_txt('ACQ:SOUR1:DATA?')
    buff_string = device.rx_txt()
    buff_string = buff_string.strip('{}\n\r').replace("  ", "").split(',')
    buff = list(map(float, buff_string))
    return buff

I learn the code in forum and improve it:

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def get_source_data(device):
    device.tx_txt('ACQ:START')
    device.tx_txt('ACQ:SOUR1:DATA?')
    buff_string = device.rx_txt()
    buff_string = buff_string.strip('{}\n\r').replace("  ", "").split(',')
    buff = list(map(float, buff_string))
    return buff

Now the codes can update plot normally but sometime it get a wrong data like this(signal of sine):
it look like some points suddenly drop to other side, I found these sample points are near together(like 1510 and 1511).
If I set the DEC to 32 or more,it will disappear in plot,but some time it will be suddenly arise again.
I need to know why and how to resolve this problem,thinks.

[redpitaya]

Hello sophistGuapi,

Thank you for writing on the forum.

Yes, the ACQ:TRIG:FILL command only works on OS versions 2.00-15 and above. This is mentioned in the documentation, but we will include notes in the examples as well.

The issue you are experiencing might be related to Red Pitaya not having enough time to capture the data, before being asked for more. The Red Pitaya always captures a buffer of 16384 samples and when setting higher decimation values, the time also increases (for decimation 32 it takes 32*16384/125e6 to capture the full buffer). At higher decimations we recommend putting a time delay between ACQ:START and ACQ:TRIG command. Also your code is missing the trigger command (the trigger must be set after starting the acquisition). Like in the examples:

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rp_s.tx_txt('ACQ:START')
# insert time.sleep() here
rp_s.tx_txt('ACQ:TRIG CH1_PE')		# the trigger condition is specified here (the trigger level and other acquisition settings can be outside the while loop)

while 1:
    rp_s.tx_txt('ACQ:TRIG:STAT?')
    if rp_s.rx_txt() == 'TD':
        break