Re: [mh] For Insteon USB PLM, Keep the USB Cord Away from Other Wires

[Marc M. <ma...@me...>]

On Wed, Feb 06, 2013 at 09:42:31AM -0800, Kevin Robert Keegan wrote:
> So in my continuing effort to whittle down Insteon corruption errors I
> performed a few tests over the last few days to determine whether
> corruption can occur between the PLM and the host computer.  In short, can
> messages become corrupted on the USB line?
> 
> The answer is, yes they can.  As such, you should keep the USB line away
> from other cables and particularly power cables.  I have gone so far as to
> move my USB cable to a plug on the front of my computer.
> 
> For two days I zip tied the USB line to my computer's power cable. Then for
> two days I neatly wrapped up the USB cable and kept it away from any other
> cables.  The comparison of the two days was rather striking.  On the first
> two days I received 5 instances in which the PLM ACK'd the incorrect
> command.  In other words, it confirmed receiving a command which was not
> sent.  Generally, the commands were off by one or more bytes.  I never
> received any such errors during the second two days.  I also ran full scans
> of my network, and received more errors on the first two days than the
> second.

That is very interesting, thank you for finding that and confirming that
apparently, USB communication is actually free of error checking for
serial ports. This is very worrisome to say the least...

Marc
-- 
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/