brant@manta.UUCP (Brant Cheikes) (03/10/88)
In article <234@safari.UUCP> dave@safari.UUCP (dave munroe) writes: >I have a 3B1 and a 7300 which are connected to each other and the outside >world [...] >is it possible to take some of that neat RJ11 >cable and heads and make a "null modem" connection between the phone ports >of the two machines to give me this: > 7300 3B1 > | ph0<-----RJ11 null-modem------------->ph0| > | ph1< (unused) | ph1<--(phone line)---> > | rs232<-- printer tty ---->rs232 | From the above diagram, it appears that you hope to use both ph0/ph1 on the 3b1 for DATA connections. As far as I can tell, this is not possible. In order for the 3b1's ph1 to be used for DATA, you must have set up the 3b1 in a two phone line configuration. This causes ph0 to become a VOICE line. One restriction I've noticed (and oft lamented) is that a 3b1 in a two line configuration can NEVER use ph0 for DATA calls. In F/S 3.51, the phtoggle routine allows you to switch ph1 between DATA and VOICE, but there does not appear to be a way to set both lines to DATA, nor a way to make ph0 DATA and ph1 VOICE. This is clearly because there is only one modem chip, and it cannot be shared between two phone lines. The 7300's one line configuration allows ph0 to switch between VOICE and DATA, so from that end everything's ok. -- Brant Cheikes University of Pennsylvania Department of Computer and Information Science ARPA: brant@linc.cis.upenn.edu, UUCP: ...drexel!manta!brant
ken@maxepr.UUCP (Ken Brassler) (03/12/88)
In article <341@manta.UUCP> brant@manta.UUCP (Brant Cheikes) writes: >In article <234@safari.UUCP> dave@safari.UUCP (dave munroe) writes: >> [ dave wants to connect two computers via modems ] >> | ph0<-----RJ11 null-modem------------->ph0| > >From the above diagram, it appears that you hope to use both ph0/ph1 >on the 3b1 for DATA connections. As far as I can tell, this is not >possible. There is one other slight problem here. A null-modem cable is used for connecting two rs-232 ports together when you're NOT using modems. You ARE using modems, so what you need is a "null-telephone company" cable. You know, a cable that will produce a dial tone when ph0 goes off-hook, then decode the tone sequence it receives, then produce a ring signal to the other ph0, etc..... :-) -- Ken Brassler {ihnp4|qantel|pyramid|lll-crg}!pacbell!maxepr!ken
ebh@argon.UUCP (Ed Horch) (03/14/88)
In article <498@maxepr.UUCP> ken@maxepr.UUCP (Ken Brassler) writes: >>> | ph0<-----RJ11 null-modem------------->ph0| >You ARE using modems, so what you need is a "null-telephone company" >cable. You know, a cable that will produce a dial tone when ph0 goes >off-hook, then decode the tone sequence it receives, then produce a >ring signal to the other ph0, etc..... :-) No smiley needed here, Ken. That's *exactly* what's needed. There are such beasts sold for telephone testing. Although I can't provide specifics, I'd imagine such a box wouldn't be cost-effective for this kind of application, though. Telecom test eqipment tends to be hideously expensive because of low sales volume and also because of the mountains of specs this kind of equipment has to meet. AT&T builds (built?) a telephone interface board for the unix-pc that was designed to be used for voice-mail type applications. I used to know the details of this thing's hardware (Craig? Jonathan?). It sounded like a neat thing to do simple call-processing on. I also remember that'it was kind of expensive (>$1K) including software, and it, like the tape system, was *not* discounted during the fire sale. Might be worth looking into, though. (Anyone got one for sale? :-) -Ed Horch