Date   : Wed, 21 Oct 1992 12:01:20 GMT
From   : eru.mt.luth.se!lunic!sunic!corax.udac.uu.se!tdb!mikaelk@bloom-beacon.mit.edu (Mikael Kristoffersson)
Subject: Re: 5v out serial port

jmolinari@hamp.hampshire.edu wrote:
:      Anybody had their serial port NOT put out the 5 volts it's supposed to?
: Anybody care to take a guess at how diffucult it would be to fix?
: 

Common seral ports use RS232 or V.24 standards for their signals. The
signal leves is for binary "0" +3 to + 25 volt. This is also used for high
level on the signal leads. Binary "1" is -3 to -25 volts, also used as low.

The use of +-12v is very common. 0V as low and 5V as high is actually NOT
supported, but it occurs... (and works most of the time...)

That's it

/Mikael Kristoffersson