Is USB fault tolerant for remote system?

USB PICs and the UBW

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Dyrl
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Joined: Tue Feb 28, 2012 1:19 pm

Is USB fault tolerant for remote system?

Post by Dyrl » Tue Feb 28, 2012 1:29 pm

Hello everybody,

I starting a development where I am thinking of using a USB to serial device in order to transmit time-critical information.
This device would have to stay on a remote environment without any user interaction. Does USB is realiable enough to run 365/24/7, and on the event of an error, could it reinstate the correct behavior without any operator/mainteinance help?

By the way, I am running an Ubuntu based distribution.

Best Regards,
Dyrl

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EmbeddedMan
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Joined: Sun Mar 05, 2006 9:23 pm

Re: Is USB fault tolerant for remote system?

Post by EmbeddedMan » Wed Feb 29, 2012 1:03 pm

Dyrl,

I think the answer is yes. If I were you, I would create a way to force the USB device to disconnect and reconnect from the bus under Linux control. For example, put a relay inline with the USB 5V line to disrupt power. Then write a daemon on the Linux side that monitors the USB connection. If too long has gone without a valid message, or if there was some funky message from the USB system under Linux, then you can start to take steps to correct the situation, like toggling the relay, or restarting the USB system under Linux. You _should_ never need this, but it would be a good safety net just in case.

There are system that rely upon USB and have very high uptimes.

*Brian

nicsky
Posts: 1
Joined: Wed Oct 03, 2012 3:13 am

Re: Is USB fault tolerant for remote system?

Post by nicsky » Wed Oct 03, 2012 3:20 am

Whilst USB is reliable at best. I dont think you can rely on it for 24/7 connection without some form of fault recovery , which may be more complicated than initially thought.
See this article
http://www.ecnmag.com/articles/2011/11/ ... d-more-usb
The article suggest that ethernet is better because of its more robust physical layer and better support for error correction etc.
I know that usb can behave very differently on different computers and it is not realy designed to be a high reliability io system
Good luck

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