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Test bench setup USB connectivity issues with USB hubs
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smoothVTer:
In our lab, I have a test bench with 10 instruments connected to a USB 3.0 hub which goes into a Windows 10 lab PC.     The VISA driver lib for everything runs on the "Keysight IO Libraries" with the included "Keysight Connection Expert 2022" software.    I typically run test suites scripted together with python, and it works 95% of the time with being able to communicate with all instruments on this 10-port USB hub. Occasionally one or more of the instruments ceases communication.  It appears X'd out in the Keysight Connection Expert.  Typically the instrument will not communicate again until I power it down, then power it back it, then restart windows, and then unplug the entire hub in the newly-booted PC and then replug the hub into the PC.  Half the time Windows issues the warning: "USB Device Not Recognized" on one of more of the DMMs ( usually this trouble instrument is a 34461A), and I have to run the entire sequence again until, by some miracle magic, coms are restored again on all instruments.

Instruments are 2000's era Keysight DMMs, scopes, R&S power supplies;  some older equipment from 1990's is still in use from Agilent, Tektronix etc. 

I've tried looking up forums for the manufacturers for USB coms issues, but quickly descend into googling-hell with half answers that go nowhere, or answers that are first seem plausible but then discover the issue is something else completely.   Trying to contact the manufacturers for advice is likewise an effort in futility, as there seem to be too many variables to get sensible answers.   I am also no guru in debugging USB protocols and anything windows related.

-- Does anyone else on here have experience controlling 10+ USB instruments using the Keysight IO libraries and has solved problems like I describe above?
-- Anybody have a brand of USB hub that perhaps are made specifically for this purpose:  Controlling many lab instruments at once?    I've googled hubs for this purpose, but I am looking for anecdotes in real-usage scenarios from any of you.
-- Anybody have an opinion on USB3.0 vs USB2.x hubs for these purposes?  Could somehow a USB3.0 hub be "too fast" for some of these older instruments?
-- Any other advice or anecdotes on USB control of 10+ instruments would be beneficial.

Thanks all!


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