[Nut-upsuser] R: NUT and relay on USB

Charles Lepple clepple at gmail.com
Wed Jan 21 00:09:58 UTC 2015

On Jan 20, 2015, at 9:32 AM, Maurizio Iacaruso <maurizio.iacaruso at gmail.com> wrote:

> Setup that I was on mind is a little different, but I think your setup works well.
> In my setup the HUB is connected directly to the UPS, then the cables go to raspberry and device.
> In your setup the HUB is connected directly to the raspberry, then the cables go to UPS and Device.

well, actually, I was describing a scenario with three standard A->B cables. In my mind, the presence of an A-to-A cable indicates a problem in the design :-)

Wait, are you just trying to use the UPS for 5VDC power over USB for the other device?

The diagram I drew shows how to connect the UPS to the RPi for monitoring, through the hub. Other configurations are possible if you don't need to monitor the UPS.
> It’s Ok?
> In both configurations I need the same things: Male B->female A adaptor, HUB  and 2 male A-> male A cables.
> The male A- male A cables have any peculiarity? Can I buy it or make it myself without problems?

The "non-standard" designation for the A-to-A cable means that it can't be used for normal USB communications, but it might work for supplying 5VDC.

> Thanks a lot for advice.
> Da: Charles Lepple [mailto:clepple at gmail.com] 
> Inviato: martedì 20 gennaio 2015 14:23
> A: Maurizio Iacaruso
> Cc: NUT List
> Oggetto: Re: [Nut-upsuser] R: NUT and relay on USB
> On Jan 20, 2015, at 7:43 AM, Maurizio Iacaruso <maurizio.iacaruso at gmail.com> wrote:
> I connect USB A (female) to USB B (male) adapter -> HUB -> 2 USB wires male
> to male,  one to raspberry and another one to my device.
> I'm not sure I understand your setup.
> This should work, using standard USB cables:
>  <- upstream       downstream ->
>      <- host       device ->
>             A->B   A->B
> Raspberry Pi -> hub -> UPS
>                  |
>                  \---> device
> The problem is that there is no equivalent of a "crossover cable" or "null-model adapter" for USB. (I am ignoring USB OTG for the moment, since you want the RPi to talk to the UPS). There are many USB adapter cables out there that will only work for supplying power, or only with point-to-point USB OTG.
> -- 
> Charles Lepple
> clepple at gmail
> _______________________________________________
> Nut-upsuser mailing list
> Nut-upsuser at lists.alioth.debian.org
> http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/nut-upsuser

Charles Lepple

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