amiguy@pnet01.cts.com (Sean Wolfe) (01/06/88)
This is a Help me question for the hardware wizzes. Ok, I bought a used RS232 terminal capaible from 50 to 19.5Kbaud, great. Now, I need to know how to make a null modem cable. Of course my standard Amy to Modem cable doesn't work... The Terminal is standard: 1 Frame Gnd. 2 Transmit Data Output 3 Rec. Data Input 4 Request to send out. 5 Clear to send input 6 Data Set Ready Inp. (opt.) 7 Sig. Gnd. 8 Carrier Dectect Input 20 Data Term. Ready Output 9 20 mA ... 14 20 Ma... 10 Detected Current Loop data 25 Current Loop + transmit 13 Current Loop - transmitt 12 Current Loop + reveice 24 Current Loop - Receive --------^^from the terminal manual-^^^^------------- So, what do I match the Amiga pinout's with on this? I've tried the following: AMIGA TERMINAL ------------------------- TD RD RD TD RTS CTS DCD DSR RI DTR GND GND DCD RTS CTS DTR DSR RI But It doesn't quite work, in fact Not at all..... Also, Among the many dip switches are #8 DCD Disconnected and DCD Conneceted #9 DSR " " DSR " " #10 DTR " " DTR " " The others I fugured out such as Baud. The terminal is a TeleVideo Mod 920 c by the way... I got it for $35.00 Works in a local mode... Can anyone help me get this thing going.. Thank's In Advance, Sean
nkhan@polyslo.UUCP (Randy Casey) (01/07/88)
In article <2287@crash.cts.com> amiguy@pnet01.cts.com (Sean Wolfe) writes: >This is a Help me question for the hardware wizzes. > >Ok, I bought a used RS232 terminal capaible from 50 to 19.5Kbaud, great. >Now, I need to know how to make a null modem cable. >Of course my standard Amy to Modem cable doesn't work... >The Terminal is standard: >1 Frame Gnd. 2 Transmit Data Output >3 Rec. Data Input 4 Request to send out. >5 Clear to send input 6 Data Set Ready Inp. (opt.) >7 Sig. Gnd. 8 Carrier Dectect Input >20 Data Term. Ready Output 9 20 mA ... >14 20 Ma... 10 Detected Current Loop data >25 Current Loop + transmit 13 Current Loop - transmitt >12 Current Loop + reveice 24 Current Loop - Receive > Sean The correct Pin connections for a Null-Modem cable are as follows: Computer Terminal -------- -------- Pin # 1 1 Pin # 2 3 Pin # 3 2 Pin # 4 5 Pin # 5 4 Pin # 6,20 (*) 8 Pin # 7 7 Pin # 8 6,20 (*) (*) For these pins jumper pins 6 and 20 on the same connector together and then run from pin 6 to pin 8. If this is for a Amiga 1000 MAKE SURE pins 14, 21, and 23 on the amiga serial cable are disconnected! You can fry the terminal, the Amiga or BOTH if these power leads get shorted. This has worked for anything I have ever needed to connect but if you still have problems Mail me at the address below. Randy -- ihnp4!psivax!csun \ | >!polyslo!nkhan | Centeral Coast Amiga Network ucbvax!sdcsvax!sdsu/ | Try Us You'll Luv It!! nkhan@polyslo.UUCP |
rap@dana.UUCP (Rob Peck) (01/08/88)
In article <2287@crash.cts.com>, amiguy@pnet01.cts.com (Sean Wolfe) writes: > This is a Help me question for the hardware wizzes. > > Ok, I bought a used RS232 terminal capaible from 50 to 19.5Kbaud, great. > Now, I need to know how to make a null modem cable. > Can anyone help me get this thing going.. > Thank's In Advance, > Sean The following cable is what I have used for the past few years as a null modem cable between any two computers: 1. At each end, I hardwired pin 4 to pin 5. 2. At each end, I hardwired pins 6 to 8 to 20. 3. From connector 1 to connector 2, I wire pin 7 straight through. 4. From connector 1 to connector 2, I wire: pin 3 pin 2 pin 2 pin 3 thats all! It works just fine with all of my terminal programs to transfer files from Amy to a Kaypro 2X, a SUN-2, or an Apple running a Prometheus multifunction (serial) card. Rob Peck ...ihnp4!hplabs!dana!rap
stu@splut.UUCP (Stewart Cobb) (01/16/88)
[mailer food] There's been some discussion of the failings of RS-232 here. This is one of my pet peeves. I think I have a solution ... (The following has little relevence to the Amiga specifically. However, Amiga owners tend to be among the most technically literate computer people around, and I've been looking for a few such to bounce these ideas off.) Let's agree that we need a new interface, one that's as widespread as RS-232, but much more standard. What are some desirable characteristics? - easy to connect (like modular phone jacks) - easy to use (smart six-year-olds can hook it up) - fast (say, 56 kbps) - standard (everyone uses it, and they all use the same "it") - backward compatible (to some extent, anyway) It's not terribly hard to design such a thing. The real trick is, once you've designed it, getting the *WORLD* to switch over. I had a bright idea along these lines about two years ago. I would write up this interface idea, and send it in to Byte. Byte would print it, all the gurus in the micro world would read it, we'd have a big meeting somewhere where we'd all agree to use it forevermore -- and six months later, it would _be_ the new standard. I wrote up the article. Byte bounced it. Sigh. That was about a year ago. I've been rewriting the article for another try, but it's a low priority. The problem is, I don't see anyone switching to a new interface unless _everybody_ does. And the only way I can think of to get _everybody_ to switch is to get them all together in the same room for a "pledge of allegience." If each manufacturer can look around and see everyone else, and know that he won't be out alone in the cold next year, then it will happen. But I can't see it happening any other way. Anyone who makes himself incompatible with RS-232 (and Centronics), without simultaneously becoming compatible with something just as widespread, is getting ready to lose his shirt. Note that this is a political problem, not a technical problem. The specific technical details of the interface are irrelevant. What matters is getting all the gurus of the micro world together. That takes publicity, in a place where all the gurus will see it simultaneously. That is (or was until recently) Byte. I can't think of another forum which cuts as large a swath across the industry. Not even the nets are that widely read. This is where you come in. What am I overlooking? Or am I barking up the wrong tree completely? If anyone has ideas or suggestions, I'd love to hear them. I sort of burned out on this a year ago, but the recent spate of complaints has gotten me interested again. RS-232 has definitely outlived its usefulness! ---------------- To the guy who wanted hermaphroditic connectors: use the Bell system trick instead. Look at your modular telephone. All the boxes (and wall jacks) have sockets. All the cables have plugs on both ends. You can wire the cables to do the RX-TX crossover automatically, and then ALL your sockets will look the same. This is probably the right way to do it. -- | Stewart Cobb (Hacking GNC for STS) ... sun!housun!nuchat!splut!stu | N5JXE @ KA5KTH or WB5BBW ... seismo!soma!uhnix1 / | << Insert the usual disclaimer >> ... hoptoad!academ / | Sattinger's Law: It works better if you plug it in.
peter@sugar.UUCP (Peter da Silva) (01/17/88)
In article <332@splut.UUCP>, stu@splut.UUCP (Stewart Cobb) writes: > - easy to connect (like modular phone jacks) > - easy to use (smart six-year-olds can hook it up) > - fast (say, 56 kbps) > - standard (everyone uses it, and they all use the same "it") > - backward compatible (to some extent, anyway) How about Midi? It's something like 30 kbps, it's become a standard, and you can hook RS232 stuff up with minimal hacking, either way. An RS232 to Midi adaptor costs about $50, so you don't even have to get rid of your RS232 equipment. -- -- Peter da Silva `-_-' ...!hoptoad!academ!uhnix1!sugar!peter -- Disclaimer: These U aren't mere opinions... these are *values*.
keithd@cadovax.UUCP (Keith Doyle) (01/21/88)
In article <1407@sugar.UUCP> peter@sugar.UUCP (Peter da Silva) writes: .In article <332@splut.UUCP>, stu@splut.UUCP (Stewart Cobb) writes: .> - easy to connect (like modular phone jacks) .> - easy to use (smart six-year-olds can hook it up) .> - fast (say, 56 kbps) .> - standard (everyone uses it, and they all use the same "it") .> - backward compatible (to some extent, anyway) . .How about Midi? It's something like 30 kbps, it's become a standard, and .you can hook RS232 stuff up with minimal hacking, either way. An RS232 to .Midi adaptor costs about $50, so you don't even have to get rid of your .RS232 equipment. Except for the minor detail that MIDI is not bidirectional. It's a one-way link. But then you can do what the MIDI people do, and use one cable for send, and one for receive. The Atari ST achieves a bidirectional link (when using it for networking) presumably by diverging from MIDI spec. Keith Doyle # {ucbvax,decvax}!trwrb!cadovax!keithd Contel Business Systems 213-323-8170
haitex@pnet01.cts.com (Wade Bickel) (01/21/88)
I'm the one who suggested the hermorphaditic cables. I prefer this
approach as opposed to the solution used by the phone company in that with
hermorphaditic cables, cables can be connected to one another to form longer
cables, adding great convienience. Also, only one connector design is needed,
where'as the otherway you have two. These both seem highly desirable features
not incorporated at the current time.
I would further suggest that the power and ground wires be specified
by voltage, so that ports with differing power ratings would never cause a
short. Everbody messes up once in a while!
As far as getting people together to form a standard, this is kind of
what ANSI and IMSA (??) are about. They make up poorly thought out standards.
It seems that the best designs come from engineers facing an immeadiate design
problem. I think my solution is fairly well thought out. I have not received
any mail to the contrary so?
To serve as a bridge between hermorphaditic cables and the current
RS-232 "standard", simply provide male/female RS-232 adapters for the new
cable.
Any body see some problem with this idea?
Thanks,
Wade.
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