LeCroy: WaveSurfer 3000/3000Z averaging mode doesn't work

[qberthet]

First, thanks for this wonderful piece(s) of software!

Each time I try an aquisition (normal, one shot or immediate) with a LeCroy WaveSurfer 3034z (using vicp), application crash with the following console log :

terminate called after throwing an instance of 'std::out_of_range'
  what():  basic_string::substr: __pos (which is 15) > this->size() (which is 2)
Aborted (core dumped)

And on the scope events log I see:

command <VBS? return = app.Aquisition.C1.AverageSweeps> at token <>:parameter cannot be interpreted by this command

The scope seems nonetheless to perform the aquisition. As this is my first time playing with ngscopeclient this might be well be a misuse from my side. I have played with different sample rate and memory depth without success.

Versions:
ngscopeclient v0.1-46-g73d93a96
libscopehal v0.1-35-g930070aa
Ubuntu 22.04.5
scope firmware version 11.2.0.0 (build 407872)

[azonenberg]

Moving this to scopehal since it sounds like a driver bug

[azonenberg]

This looks like an issue with averaging mode, maybe the 3000Z series used a different command than other MAUI based scopes for it.

Give me a few minutes and I'll push an update that disables averaging on the 3000Z. If that fixes the problem we'll leave it disabled; at some point in the future we can figure out what the right commands to send are and re-enable it.

[azonenberg]

Just pushed an update to libscopehal that should fix the crash (but also disables the averaging feature entirely on WaveSurfer 3000 family scopes) as well as the corresponding update to scopehal-apps (ngscopeclient/scopehal-apps@c87dae3)

You should be able to either build latest scopehal-apps from source (don't forget to do a recursive pull to get the latest scopehal when you do this) or wait a few minutes for the CI builds to finish and grab the binaries from there.

Let me know if it works. I'll keep this issue open until we fix averaging mode entirely, but if the crash is gone it will be de-prioritized.

[qberthet]

Thanks for the quick fix, I'll confirm when I am near the scope again.

[qberthet]

I confirm that the fix do indeed work, I am now able to aquire a waveform.

As we also have a Wavesurfer3034 (not z), I confirm that the fix still work with the non-z model (at least the 3034), but I also confirm the non-z was also crashing with initial report version (v0.1-46-g73d93a96).

This issue can be closed but I am available to help if there is interest to investigate how to enable averaging on these models.

[qberthet]

Maybe spoke a bit too soon : Aquisition works but when I try to change the sample rate I get the following error on scope events log (no crash):

command <VBS? app.Acquisition.Horizontal.SampleRate = 500000> at token <>: parameter cannot be interpreted by this command

[azonenberg]

I'll keep this issue open and retarget it for "averaging mode does not work on WS3K series".

The WaveSurfers run a heavily forked version of the full MAUI software stack ported to Windows CE and change a bunch of APIs so avoiding bitrot of them while working on the driver is challenging. I started out on one (a 3034 was actually my first LeCroy scope) but sold it years ago and while I occasionally still go to the lab it now lives in, I don't have routine daily access to it without a significant commute.

Can you file a separate issue for the sample rate problem? It's lower priority but we still want it documented for when someone has time to poke at it.

As far as how to fix it properly, you're going to want to install LeCroy's older remoting software, WaveStudio (https://www.teledynelecroy.com/support/softwaredownload/wavestudio.aspx). It should come with an "XStream Browser" or similarly named application that you can connect to the scope with and see a sort of tree view of properties and settings. What we're looking for is the actual tree path of the settings in question, which has likely changed in the forked firmware for low-end scopes vs "regular" MAUI (which runs on full desktop Windows on an x86 mainboard on LeCroy's higher end scope families like WaveRunner and HDO)

[azonenberg]

Higher end LeCroy scopes let you minimize the scope GUI and jump straight to a Windows desktop. You can then use the touchscreen (or plug in a mouse and keyboard) to launch XStream Browser directly on the scope, which is how I do most of my driver development.

The Windows CE based ones don't give you that option, so you have to run the browser on a Windows PC (or a higher end LeCroy scope lol) and connect it to the scope, I believe via DCOM (yes) to see the properties tree.