wargo@sdcsla.UUCP (Dave Wargo) (05/31/85)
*** REPLACE THIS LINE WITH YOUR MESSAGE *** *** NO WAY JOSE *** Here is some RS232 info that worked for me. I have used the cable to talk to my VAX with no problems. I think I will try to use it to talk to another mac. This could be fun..... By the way all the stuff after this is from other bright people and they should get the credit. Dave Wargo ucbvax!sdcsvax!sdcsla:wargo *********************************************************************** >From sdcsvax!dcdwest!ittvax!decvax!tektronix!tekig1!briand Article 639 of net.micro.mac: Relay-Version: version B 2.10.2 9/18/84; site sdcsla.UUCP Posting-Version: version B 2.10.2 (Tek) 9/28/84 based on 9/17/84; site tekig1.UUCP Path: sdcsla!sdcsvax!dcdwest!ittvax!decvax!tektronix!tekig1!briand >From: briand@tekig1.UUCP (Brian Diehm) Newsgroups: net.micro.mac Subject: Re: Mac-tty pinouts? Message-ID: <1841@tekig1.UUCP> Date: 18 Feb 85 19:19:23 GMT Date-Received: 25 Feb 85 00:09:02 GMT References: <2362@nsc.UUCP> Distribution: net Organization: Tektronix, Beaverton OR Lines: 25 >From postnews Mon Feb 18 11:17:37 1985 > Sigh. I've asked this before, and succeeded in misplacing the answers. Can > someone drop me a note with the pinouts I need to get a Macintosh to tie > into an RS232 line? *** REPLACE THIS LINE WITH YOUR MESSAGE *** *** NO! *** The following four connections will make your Mac RS-422 connector into a standard RS-232 connector. Building a cable with a female 9-pin D connector on one end and a female (or male, depends upon your modem) 25-pin D connector on the other is the easiest way to do this. RS-422 RS-232 (Mac 9-pin) (Modem 25-pin) 3 7 5 2 7 20 9 3 Good telecommuning! -Scott Phillips Tektronix, Inc. >From sdcsvax!sdcrdcf!hplabs!hao!seismo!rochester!ur-univax!ning Article 760 of net.micro.mac: Relay-Version: version B 2.10.2 9/18/84; site sdcsla.UUCP Posting-Version: nyu notesfiles V1.1 4/1/84; site ur-univax.UUCP Path: sdcsla!sdcsvax!sdcrdcf!hplabs!hao!seismo!rochester!ur-univax!ning >From: ning@ur-univax.UUCP Newsgroups: net.micro.mac Subject: Re: Mac-tty pinouts? Message-ID: <16500011@ur-univax.UUCP> Date: 5 Mar 85 21:13:00 GMT Date-Received: 9 Mar 85 09:54:20 GMT References: <2362@nsc.UUCP> Organization: University of Rochester: Computing Center Lines: 55 Nf-ID: #R:nsc:-236200:ur-univax:16500011:000:2159 Nf-From: ur-univax!ning Mar 5 16:13:00 1985 > The following four connections will make your Mac RS-422 connector into a > standard RS-232 connector. Building a cable with a female 9-pin D connector > on one end and a female (or male, depends upon your modem) 25-pin D connector > on the other is the easiest way to do this. > RS-422 RS-232 > (Mac 9-pin) (Modem 25-pin) > 3 7 > 5 2 > 7 20 > 9 3 I have just finish building an RS-232 cable for my Mac/modem, and it works beautifully. But I didn't use the diagram above, and unfortunately, the diagram above doesn't work with software that looks for the RS-232 signal called DCD (Carrier Detect). The problem is the way it uses the pin 7-to-20 connection. Pin #7 on the Mac is a "listen" line called HSC (High-Speed Carrier?) in RS-422 lingo. Pin #20 on a DB-25 is a "talk" line called DTR (Data Terminal Ready) in RS-232 lingo. The problem is that a modem doesn't send a DTR signal. (It sends a DSR (Data Set Ready) on pin #6, but this is irrelevant, because the Mac is looking for a "Carrier Detect.") The right connection for a DCD is pin #8 on a DB-25. Now that the two "carrier detects" are hooked up, this is what happens. The Mac tells the modem to dial, and when the modem gets the carrier from a remote modem, it makes true the DCD line. When the Mac "hears" a true from its HSC line, then it knows that a distant modem has been hooked-up. Of course, software that ignores the DCD will work, but it might get you sometime in the future. I used the diagram found in the "Open Window" section in March's issue of MacWorld. The article there shows how to hook a Mac up with a Volksmodem. So, I simply matched the signal *names* from the Volksmodem with a D-25 connector. This was my end result: Macintosh Modem RS-232 Signal Name (9-pin DTE) (25-pin DCE) Pin # 3 <---> 7 Signal Ground (GND) 5 ----> 2 Transmit Data (TxD) 9 <---- 3 Receive Data (RxD) 7 <---- 8 Data Carrier Detect (DCD) Note that a cable built this way will also work for a simple RS-232 line to a mainframe. John Lam______________________________________ {allegra,seismo,inhp4}!rochester!ur-univax!jnl PS. No flame intended. (:-)