Unexpected aquisition behavior over SCPI

[Concept]

Hi,

I found an unexpected behavior of the Red Pitaya when used via the SCPI.
Generally all seems to be working great, I can control all I/Os the generators and the RF inputs.
However, when I tested the acquire functions I found that if I try to measure a single pulse generated by an external waveform generator there is only noise in the buffer.
This happens when I control the Red Pitaya from Scilab.

I use the following sequence:
- Set up sample rate
- Set trigger level
- Set trigger delay
- ACQ start
- Set trigger source

The trigger status is as expected when I send a pule from the waveform generator (so triggering seems to work) but when I read the buffer there is only noise.
(Same with official sample code http://redpitaya.com/make-your-app/sing ... r-acquire/)

Now the weird thing is that if I start the scope web application ones before I run my SCPI implementation everything works as expected.
So it seems like there is some setup/initialization step necessary that I miss.

Has anybody else observed such an issue?
Any idea what I am missing?

Thanks a lot for the help in advance!

[BrunoDerbaer]

Hello Concept,

I have exactly the same problem using Matlab and the official sample code: Synchronised one pulse signal generation and acquisition.
Running the sample I get only noise after triggering. Running the scope app in parallel and adjusting it for single aquisition I get a perfect pulse as expected.

Did you find a solution for this problem in the mean time?

Does the original sample code work for anybody?

Best regards
Bruno

[redpitaya]

Hi guys,

Which version of OS you are using?
We will look at it.

Best,RP

[Concept]

Hi,

I am using v.094-RC19.
I also found the root cause for it.

With the current SCPI version you can not set the trigger mode to "Normal" or "Single".
So the trigger is always set to Auto.

You can change that by starting the scope app and setting the trigger there to "Normal".
I used an older version of the SCPI server that still had the OSC:XXX commands. Those actually included the option to set the trigger mode.

Please refer to my forum entry "SCPI commands changed/not working in 0.94".
That shows multiple other commands that are not working with the current examples. The reason is the changed SCPI and some of the missing commands.

All the best!
Hans