Single shot trigger via SCPI

[hadmack]

I would like to readout out simultaneous waveforms from channel 1 and 2 via the SCPI interface but I can't seem to get the trigger set up correctly. I am generating a sine wave on output 1, reading the output directly on input 1. Input channel 2 is looking at the same signal on a fixed voltage divider. These waveforms are identical except for attenuation but the data I read using the prescription below give a random phase between channel 1 and 2. I think that the board is retriggering between the time that I can readout channel 1 and the time I read out channel 2 so that I don't get synchronous data. I do issue an ACQ:STOP to prevent this from happening. I appreciate any advice on what is going on here.

ACQ:RST
ACQ:DEC 8
ACQ:TRIG:LEV 0
ACQ:DATA:UNITS RAW
ACQ:TRIG CH1_PE
ACQ:START
wait for ACQ:TRIG:STAT? == TD
ACQ:STOP
ACQ:SOUR1:DATA:STA:N? 0 4096
ACQ:SOUR2:DATA:STA:N? 0 4096

[evpator]

I have the same problem. Actually you can see this problem with Decimation factor lower than 64. As I think the reason is that during reading data from ADC buffer into SCPI server (which is slow) the buffer is continuosly updated with new ADC conversion values (which is much faster up to 125 MS/s).
This makes almost impossible to acquire fast sample rate data by SCPI server. Probably one need to change SCPI server behavior in a way that for a reading session by SCPI the buffer values should freeze...

1) Other problem is the ACQ:STOP is not working properly.
Example: try after ACQ:STOP several time to apply ACQ:WPOS?, You will see that writing counter is still running after ACQ:STOP and data in ADC buffer is changing.

2) Actually it would be nice to have separate folder in Forum for SCPI related problems. To have SCPI by RedP is nice and very wishable, but at the moment current realisation of SCPI is buggy.

3) There is also some logical problems with Trigger control by SCPI: at the moment there is no possibility of single trigger on different channel edges. Typically by oscilloscopes trigger modes (auto/continuous, normal and single) are separated from the trigger sources (channel and edges)