Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 5/3/83; site utcsrgv.UUCP Path: utzoo!utcsrgv!info-mac From: info-mac@utcsrgv.UUCP (info-mac) Newsgroups: ont.micro.mac Subject: Re: Query on rs232/422 mac connectors Message-ID: <4300@utcsrgv.UUCP> Date: Wed, 16-May-84 09:30:40 EDT Article-I.D.: utcsrgv.4300 Posted: Wed May 16 09:30:40 1984 Date-Received: Wed, 16-May-84 10:01:04 EDT Sender: peterr@utcsrgv.UUCP Organization: CSRG, University of Toronto Lines: 32 Date: Mon 14 May 84 22:18:34-PDT From: Joseph I. Pallas Subject: Re: Query on rs232/422 mac connectors To: farber@UDEL-EE.ARPA Cc: info-mac@SUMEX-AIM.ARPA In-Reply-To: Message from "Dave Farber " of Mon 14 May 84 17:39:58-PDT We are getting about 2.5 volts out of our mac on pin 7. Is that normal? I believe the specs for rs232 say > 3 volts It can't be considered abnormal, since (according to the pinout in macintosh.rs232) pin 7 is an input. The Mac represents an rs232 Data Terminal, not Data Set. If you're talking to a modem, pin 7 should go to rs232 pin 5. The connections I used are: Mac Modem 3 7 5 2 7 5 9 3 Some modems will want to see DTR (pin 20) active also, which can be faked by tying it to pin 5 (I'm not sure if that's the canonical way to fake it, though). Other modems will ignore DTR or can be made to (e.g., USR Password has a switchable option). Hope that helps! joe -------