[ntp:questions] Re: Meaning of PPS flag2 -- assert/clear

David Woolley david at djwhome.demon.co.uk
Sun Oct 15 19:19:23 UTC 2006


In article <1daa04-sad.ln1 at robert.houseofmax.de>,
Uwe Klein <uwe_klein_habertwedt at t-online.de> wrote:

> an unconnected RS232 Receiver Hardware pulls high (+3V++)
> 	signaling RX=L and thus (LINE)BREAK if
> 	this continues longer than one legal frame
> 	i.e a broken line

An unconnected RS232 receiver pulls to control signal false, so to data
mark.  It's current loop interfaces that fail to spacing.  That may
well be why the data is inverted with respect to the controls.

Part of the cofusion here is that assert only applies to the control
signals, so, if you try and use it for data, you do end up with 
0 being the asserted state!




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