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

[Charles Lepple]

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



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