[time-nuts] Does the Thunderbolt have to be connected to a real serial port?

[Samuel D. [x86/CPC]]

> The good output +/-9V or more as the spec requires.

According to the official RS232C specifications, the valid voltage range
must be between +/-3V and +/-15V (+/-25V for the first draft). A device that
absolutly require +/-9V is not RS232 compliant. BTW, as you said, some cheap
USB<->Serial adapters output 0/+5V TTL levels and don't work with many
devices.



-----Message d'origine-----
De : time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] De la
part de Poul-Henning Kamp
Envoyé : vendredi 20 février 2009 20:55
À : Discussion of precise time and frequency measurement
Objet : Re: [time-nuts] Does the Thunderbolt have to be connected to a real
serial port?

In message <499F09E5.4020300 at xs4all.nl>, "S. Nestra" writes:

Quite a lot of USB-serial adapters cheat at various levels.

The worst output 0/+5V or +/-2.5V  either of which are totally outside the
spec at the receiving end.

The acceptable output +/-5V, which i out of spec for a transmitter, but
inside spec for a receiver, so a short or no cable, it works fine.

The good output +/-9V or more as the spec requires.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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