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From: prestonb@hpcvra.CV.HP.COM (Preston Brown)
Newsgroups: comp.sys.handhelds
Subject: Re: 48sx serial voltage levels
Message-ID: <21580025@hpcvra.CV.HP.COM>
Date: 13 Mar 90 23:04:33 GMT
References: <4927f2ed.bfe8@tachyon.engin.umich.edu>
Organization: Hewlett-Packard Co., Corvallis, OR, USA
Lines: 16

>It is my understanding that RS232 signal levels are +/-12Volts. Does the
>48sx opperate at these levels, or does the HP interface kit do level
>conversion?

I posted some info on the signal levels earlier today, the 48SX outputs
+/- 3Volts and no level conversion is necessary since the spec for an
RS232 reciever is +/-3Volts also.

>If you haven't guessed, I want to make a cable, but am afraid of frying
>an $n10^2 calculator.

Don't worry the 48SX serial port includes protection circuits to handle
up to +/- 25V on any pin.  Just be careful with the connector it is easy
to bend a pin on the connector.

Preston