pmc@caen.engin.umich.edu (Paul S McClay) (03/12/90)
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 am surprised that 3 AAA batteries contain the juice to run an RS232 port for more than a week, but nobody has mentioned any special attributes of the interface cable... If you haven't guessed, I want to make a cable, but am afraid of frying an $n10^2 calculator.
prestonb@hpcvra.CV.HP.COM (Preston Brown) (03/14/90)
>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