[ntp:questions] ntp server specs

Chuck Swiger cswiger at mac.com
Tue Jun 14 21:58:01 UTC 2011

On Jun 14, 2011, at 12:52 PM, Chris Albertson wrote:
[ ... ]
> The problem with both of those is that the Linux machines are all
> going to want the PPS to be conected to the DTR pin of a serial port
> and for that you need rs-232 levels with wides plus and minus volts.
> TTL level or wose is not going to work.

If you're distributing a serial signal to more than one receiver, you're already outside of the RS-232 spec.  While it's getting uncommon to find serial ports rather than USB nowadays, fortunately most are really RS-232 & RS-423 compatible and will trigger off of TTL voltage swings rather than needing the +/- 3V minimum of RS-232; they also are in-spec with up to ten receivers on the line.


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