[time-nuts] RS 232

Chris Albertson albertson.chris at gmail.com
Fri Jul 26 01:30:37 EDT 2013


On Thu, Jul 25, 2013 at 8:40 PM, John Miles <john at miles.io> wrote:

> > john at miles.io said:
> > > Agreed, nobody should be using RS232 for anything nowadays.
> >
> > RS232 works much better for capturing PPS timing.
>
> Unless you are watching it with a ring-0 (kernel) driver, and/or using a
> hard realtime OS to run the client software, it really won't matter that
> much.  Anyone running Windows or most flavors of Linux has more to worry
> about than the distinction between USB and RS-232, when it comes to
> latency.


In just normal UNIX (including Mac OS X) and linux you can see the
difference in the log files between USB and RS232.  There is three orders
of magnitude difference.  It's micro vs. milli seconds.

But as this filters down to the application level, what are you using this
timming informations for?  Maybe you have a database and you are time
tagging transactions?  In that case maybe all you need is tenths of
seconds.   Who knows?  THat is really what needs to be driing this process
the end use of the data
-- 

Chris Albertson
Redondo Beach, California


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