NETOPRWA@NCSUVM.BITNET (Wayne Aiken) (08/28/89)
I'm trying to hook my Apple //e and IBM AT together through the serial ports, via null modem, but it only works in 1 direction. Ideally, whatever you type on one terminal appears on the other, but characters from the IBM don't get through. I have a Hayes-compatible modem that I can hook up to the Apple, which works, but I don't get any characters back from the modem in response to AT commands. It does work, however, because it dials out from an ATDT command, and once I'm connected to a BBS, everything flows normally. When the modem is connected to the IBM, the AT commands are echoed normally. I'm using some weird clone of the Apple Super Serial card, this one is id'd only by 'SSB-1'. Am I missing something in the null modem (I'm using a breakout box to swap 2 & 3, ground 7 straight through) or should I just trash this clone serial card and get the real thing? Thanks for any help. If I can get this working, I'll soon have most of comp.binaries.apple on my (IBM) bulletin board. Wayne Aiken netoprwa@ncsuvm.bitnet "You can BE what PO Box 30904 netoprwa@ncsuvm.ncsu.edu you WON'T!!" Raleigh, NC 27622 StarFleet BBS --"Bob" (919) 782-8171 (919) 782-3095
NETOPRWA@NCSUVM.BITNET (Wayne Aiken) (08/30/89)
A couple of days ago, In article <896NETOPRWA@NCSUVM>, I asked: >I'm trying to hook my Apple //e and IBM AT together through the serial ports, >via null modem, but it only works in 1 direction. Ideally, whatever you type >on one terminal appears on the other, but characters from the IBM don't get >through. > >I have a Hayes-compatible modem that I can hook up to the Apple, which works, >but I don't get any characters back from the modem in response to AT commands. >It does work, however, because it dials out from an ATDT command, and once I'm >connected to a BBS, everything flows normally. When the modem is connected to >the IBM, the AT commands are echoed normally. >....... Am I missing something in the null modem (I'm using a >breakout box to swap 2 & 3, ground 7 straight through) or should I just trash >this clone serial card and get the real thing? Many thanks to the people who responded. The solution came from Paul Sander (paul@Atherton.COM), who said: >The problem is that the Super Serial Card does not poll the ACIA when the >Carrier Detect signal is inactive. There are three ways I can think of to >remedy the problem. Aha! That explains the behavior with the AT commands to the modem. >1. There is a switch on the card that opens the CD connection between the > ACIA and the DB-25 connector. The documentation will say something like > "Set this switch to OFF for printer mode, set it ON for communication > mode." You should be able to spot it on the schematic diagram if one is > included in your docs and you know how to read it. Since I don't have a > copy of my docs with me here at work, I can't give the exact switch > setting. If you need it, send follow-up mail and I'll send the details > in return mail. No dice. The 'SSB-1' card doesn't seem to have any provision for forcing or ignoring CD. The card does have a printer mode documented, but no combination of switches seems to do the trick. But, hardly any of the niceties in the documentation seem to work on this card. >2. If your null modem can do it, open the CD connection, or route it back > to the Data Terminal Ready line on the SSC. > >3. Use a break-out box to open the CD connection. Bingo! With pins 2 and 3 swapped in the break-out box, and ground 7 straight through, the CD light on the RS232 monitor showed no signal. Connecting a jumper between CD and DTR on the Apple side of the connector worked; characters and packets now flowed freely from the ibm to the Apple. I heard from a couple of people who used only the 2x3-7 method using a real SSC; they must have had the CD forced true on the card. In response to a message posted not long ago about someone wanting to hook an Apple to some other system, be aware of this kludge if the serial card in the Apple doesn't have some way of dealing with CD. I never could get the 'SSB-1' to change from 1200 baud, nor would it perform any other 'terminal settable features', so I decided to replace it with an Applied Engineering Serial Pro card. Many thanks for this tidbit of technical info, as this wasn't at all apparent from the scant documentation for the clone. Caveat emptor. Wayne Aiken netoprwa@ncsuvm.bitnet "You can BE what PO Box 30904 netoprwa@ncsuvm.ncsu.edu you WON'T!!" Raleigh, NC 27622 StarFleet BBS --"Bob" (919) 782-8171 (919) 782-3095