making HP39GS Serial Cable (RS-232)

[ilkka777]

(05-06-2019 04:25 AM)SammysHP Wrote:  RS-232 uses voltages between -15 V and +15 V and negative logic. What you know as "RS-232" or "serial connection" uses the same binary encoding, but inverted, positive logic and TTL levels (0 V to 5 V or 3.3 V). You should always include some kind of level converter or you might destroy your components.

Thanks, is there also some kind of handshake before data is sent?