billau@hou2h.UUCP (#W.AU) (08/26/86)
I just got a modem for my mac and would like to try it out. However, my modem has one of those standard 25-pins connector instead of mac's 9-pins. I really don't want to spend too much money on a cable when I can make one myself. Could someone please send me the layouts of the pins? My modem is Hayes compatible. Bill Au ...!ihnp4!hou2h!billau
zben@umd5 (Ben Cranston) (08/27/86)
I couldn't find the 8 pin Din males anywhere, so I decided to use the
adapter cable that came with the Mac + and got myself some DB9 males
and made up these two cables:
For connecting Mac to Modem or other DCE-type Female:
DB9 Male DB25 MALE
GROUND 3 O------+----------------O 7 GROUND
XMIT DATA + 4 O-x )
XMIT DATA - 5 O------)----------------O 2 XMIT DATA
HANDSHAKE OUT 6 O---+--)----------------O 20 DATA TERMINAL READY
HANDSHAKE IN 7 O---+ | +---O 4 REQUEST TO SEND
RECV DATA + 8 O------+ +---O 5 CLEAR TO SEND
RECV DATA - 9 O-----------------------O 3 RECV DATA
This works with our three-wire Gandalf network inhouse and with a Courier
modem at home. The Mac is the new RS-422 (?) balanced protocol, and the
old RS-232 had inverted data, so the DATA - goes across and the DATA +
gets grounded to complete the circuit. Do NOT ground XMIT + !
For connecting Mac to Terminal or other DTE-type Male:
DB9 Male DB25 FEMALE
GROUND 3 O------+----------------O 7 GROUND
XMIT DATA + 4 O-x |
XMIT DATA - 5 O------)----------------O 3 RECV DATA
HANDSHAKE OUT 6 O-x |
HANDSHAKE IN 7 O------)----------------O 20 DTR
RECV DATA + 8 O------+
RECV DATA - 9 O-----------------------O 2 XMIT DATA
This works with an H19 at home and a Volker Craig 4404 at work. If your
device is persnickety it might want Carrier Detect on pin 8, if so the
connect 8 to 20 at the DB25 end (so DTR drives it). One might also have
to connect pins 4 and 5 (RTS-CTS) together at the DB25 end to make some
devices happy.
Other than that, get a breakout box and read the specs, and if it does
not work then don't leave it connected long enough to get hot...
--
umd5.UUCP <= {seismo!umcp-cs,ihnp4!rlgvax}!cvl!umd5!zben
Ben Cranston zben @ umd2.UMD.EDU Kingdom of Merryland Sperrows 1100/92
umd2.BITNET "via HASP with RSCS"graifer@net1.UCSD.EDU (Dan Graifer) (08/28/86)
I was able to obtain MiniDIN-8 connectors from my Apple dealer (Computer Merchant of San Diego). I suspect they had them leftover from before they gave up manufacturing cables themselves; The DIN-8 is B....! I've heard of others joining with a friend to buy an Apple ImagewriterII cable and cutting it in half. Anyways here is the cable I am succesfully using to connect my Mac+ to a Hayes Smartmodem 1200: Signal DIN-8 Color DB-25 Signal HSKo 1 Orange 6 DSR HSKi 2 Green 20 DTR TxD- 3 Red 2 TXD Gnd 4 Black 7 Sig. Gnd. RxD- 5 Blue 3 RXD TxD+ 6 unused 7 RxD+ 8 (ShieldRing) (FoilShield) 1 Protective Gnd The Apple Technote a friend showed me indicated that the first two should swapped. It also indicated +12v for pin 1. This didn't work, and also makes no sense: handshake output is a signal from the modem to the Mac. A voltmeter told me the +v signal was on pin 2; The smartmodem requires a +v signal on DTR ready before it will operate. The above arrangement WORKS. (you don't want to hook carrier detect (DB25 pin 8) to HSKo, as a Hayes compatable modem will accept control data when there is no carrier) Some people have suggested that pin 8 (RxD+) should be tied to ground. I havent done so, and have had no problem with the floating signal. I have also heard that grounding TxD+ can be physically damaging to the Mac. I used 9 conductor plus ground shielded cable: shielded cable is HIGHLY recommended. If you can get 5 conductor, you will have less trouble than I had getting the rubber jacket over the cable. Good luck Dan Graifer