Event handlers - is it possible for TCPIP INSTR resource?

[SimonMerrett]

I previously used NI backend but never want to let another NI software run on my new, clean machine. So I tried to use event handlers with @py backend but found that these are apparently not yet implemented in pyvisa-py. Is that correct?

If so, I'm willing to help implement with some supervision. Is this something the maintainers can give?

[MatthieuDartiailh]

In what kind of events are you interested ?

It is not a topic I have given any though but if you are interested I can try to provide some guidance.

[SimonMerrett]

I pretty much want to implement this use case: https://pyvisa.readthedocs.io/en/latest/introduction/event_handling.html#registering-handlers-for-event where I command a long set of measurements which are stored on the instrument to begin and configure it to raise a service request on completion of the measurements. When the event handler changes the flag from false to true, I can retrieve the measurement data. I have found this much more stable than polling to discover when measurements are complete.

[SimonMerrett]

Does this sound feasible for e.g. TCPIP::INSTR resource @MatthieuDartiailh?

[MatthieuDartiailh]

It should be yes. The harder part may be to get the right pieces for VXI11 (the underlying protocol). I will have a look at this tomorrow and try to draft a plan.

[SimonMerrett]

Thanks. I did ask an LLM because the whole architecture behind VISA is beyond my current comprehension as a user of test instruments. Would it be helpful if I shared any of it's suggestions/comments? I got the impression that an event listener could be implemented using threads. It also talked about needing to send on one port and then receive on another - a bit of a reverse/backward messaging approach but apparently necessary for the VXI11 stuff.

[MatthieuDartiailh]

Feel free to share what you got yes

[SimonMerrett]

@MatthieuDartiailh sorry, took me a while to format as I couldn't get a decent export: https://gist.github.com/SimonMerrett/d1db4aaa5eef2723bba459cfd4c1799b

[MatthieuDartiailh]

The outline from Gemini looks reasonable to start from. Could you prepare a PR with those changes and we can iterate from there ?

[SimonMerrett]

Yes 👍

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________________________________ From: Matthieu Dartiailh ***@***.***> Sent: Thursday, December 4, 2025 4:42:41 PM To: pyvisa/pyvisa-py ***@***.***> Cc: SimonMerrett ***@***.***>; Author ***@***.***> Subject: Re: [pyvisa/pyvisa-py] Event handlers - is it possible for TCPIP INSTR resource? (Issue #544) [https://avatars.githubusercontent.com/u/4481740?s=20&v=4]MatthieuDartiailh left a comment (pyvisa/pyvisa-py#544)<#544 (comment)> The outline from Gemini looks reasonable to start from. Could you prepare a PR with those changes and we can iterate from there ? — Reply to this email directly, view it on GitHub<#544 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AGMHBJJFAYTPBOALOFHT4F34ABQADAVCNFSM6AAAAACNXOPY7KVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTMMJTGE3DGNZTGU>. You are receiving this because you authored the thread.Message ID: ***@***.***>

[SimonMerrett]

@MatthieuDartiailh I realise a review of my PR will take time. It is failing CI tests - bearing in mind I'd need some guidance on addressing the failures as this is new territory for me, is it a prerequisite that those are passing before you will review it? Or, given the plan is to iterate from the first attempted PR, we can let that slide for now and work on the meat of the features first?

[MatthieuDartiailh]

I will do my best to review your PR by the end of the week. Let's not worry yet about the CI given the scope of the PR.

[SimonMerrett]

Thank you very much.