umcarls9@ccu.umanitoba.ca (Charles Carlson) (01/08/91)
Thanks to all those who replied to my question of whether or not I could get by without using phone net connectors on a two node network. One person said he had successfully used an IW II cable to run Appletalk from one Mac to another, but the general concensus was "Don't bother trying". One person from TOPS wrote and said I would void my warranty with TOPS if I tried that, and may even damage my Appletalk ports. So I guess I'll be ordering a couple phone net connectors! Charles
boortz@sics.se (Kent Boortz) (01/08/91)
> One person said he had successfully used an IW II cable to run Appletalk from > one Mac to another, but the general concensus was "Don't bother trying". > One person from TOPS wrote and said I would void my warranty with TOPS if > I tried that, and may even damage my Appletalk ports. So I guess I'll be > ordering a couple phone net connectors! This is very strange in my opinion. An ImageWriter cable is a standard serial cable for mac and is intended for connection of two RS-422 ports. There should be no difference electrically connecting a mac to mac, mac to modem, mac to LaserWriter or mac to ImageWriter. AppleTalk is software and I don't think software could feel the difference how you electrically connect the devices in this case. The intention of the LocalTalk box is to let you mix output signal from different ports and is needed if more than two LocalTalk equipment are connected. There is no magic in these boxes. The only problem I can think of is WHEN an equipment do some magic. This is from what I have heard the case with the DeskWriter printer. It will test the electrical condition of the serial port to determine if you are using a LocalTalk box or a straight cable and switch between AppleTalk and serial mode from this information (that would mean that you can't use the standard print spooler with an ImageWriter cable I suppose). Well, I can't promise anything. I don't use this setup myself but I can't think of any reason why a straight ImageWriter cable could damage anything. Kent Boortz boortz@sics.se
minich@d.cs.okstate.edu (Robert Minich) (01/08/91)
by boortz@sics.se (Kent Boortz): |# One person said he had successfully used an IW II cable to run Appletalk |# from one Mac to another, but the general concensus was "Don't bother |# trying". One person from TOPS wrote and said I would void my warranty |# with TOPS if I tried that, and may even damage my Appletalk ports. So I |# guess I'll be ordering a couple phone net connectors! | | This is very strange in my opinion. An ImageWriter cable is a standard | serial cable for mac and is intended for connection of two RS-422 ports. | There should be no difference electrically connecting a mac to mac, mac | to modem, mac to LaserWriter or mac to ImageWriter. A straight null-modem cable should do fine for two LocalTalk devices however, Kent is wrong about (mac<->mac) == (mac<->modem) == (LW|IW<->mac). [Did that come out right?] The exception is the modem. Serial devices come in two flavors, Data Terminal Equipment (DTE) and Data Comm. Equ. (DCE). When wiring DTE<->DCE, the pins labeled Tx (transmit) on both devices are connected together while DCE<->DCE cables have Tx<->Rx wiring, eliminating the need for a modem, thus the null-modem cable. -- |_ /| | Robert Minich | |\'o.O' | Oklahoma State University| "I'm a newcomer here, but does the |=(___)= | minich@d.cs.okstate.edu | net ever lay any argument to rest?" | U | - Ackphtth | -- dan herrick
philip@pescadero.Stanford.EDU (Philip Machanick) (01/09/91)
In article <1991Jan8.090043.25113@sics.se>, boortz@sics.se (Kent Boortz) writes: |> |> > One person said he had successfully used an IW II cable to run Appletalk from |> > one Mac to another, but the general concensus was "Don't bother trying". |> > One person from TOPS wrote and said I would void my warranty with TOPS if |> > I tried that, and may even damage my Appletalk ports. So I guess I'll be |> > ordering a couple phone net connectors! |> |> This is very strange in my opinion. An ImageWriter cable is a standard |> serial cable for mac and is intended for connection of two RS-422 ports. |> There should be no difference electrically connecting a mac to mac, mac |> to modem, mac to LaserWriter or mac to ImageWriter. |> |> AppleTalk is software and I don't think software could feel the difference |> how you electrically connect the devices in this case. |> |> The intention of the LocalTalk box is to let you mix output signal from |> different ports and is needed if more than two LocalTalk equipment are |> connected. There is no magic in these boxes. |> |> The only problem I can think of is WHEN an equipment do some magic. This |> is from what I have heard the case with the DeskWriter printer. It will |> test the electrical condition of the serial port to determine if you are |> using a LocalTalk box or a straight cable and switch between AppleTalk |> and serial mode from this information (that would mean that you can't |> use the standard print spooler with an ImageWriter cable I suppose). |> |> Well, I can't promise anything. I don't use this setup myself but I |> can't think of any reason why a straight ImageWriter cable could |> damage anything. Someone from HP told me that the only reason you can't connect a DeskWriter to a Mac in AppleTalk mode using a serial cable is they explicitly check as described above. He said there is no reason _not_ to do this in other cases. It is possible that TOPS hardware is designed differently, but in the general case, an ImageWriter II cable is quite safe to substitute for network connectors for a 2-node network. If you made up a longer cable with T-connectors for a more-than-2-node network, you can expect problems. -- Philip Machanick philip@pescadero.stanford.edu
houlejm@ireq.hydro.qc.ca (Jean-Marie Houle) (01/09/91)
In article <1991Jan8.090043.25113@sics.se> boortz@sics.se (Kent Boortz) writes: > > One person said he had successfully used an IW II cable to run Appletalk from > > one Mac to another, but the general concensus was "Don't bother trying". > > One person from TOPS wrote and said I would void my warranty with TOPS if > > I tried that, and may even damage my Appletalk ports. So I guess I'll be > > ordering a couple phone net connectors! > > Well, I can't promise anything. I don't use this setup myself but I > can't think of any reason why a straight ImageWriter cable could > damage anything. So I do. Also Tops could not see the difference... Jean-Marie Houle houlejm@ireq.hydro.qc.ca Institut de recherche d'Hydro-Quebec Tel (514) 652-8083 1800 Mtee Ste Julie Fax (514) 652-8435 Varennes, Quebec Canada, J3X 1S1
russotto@eng.umd.edu (Matthew T. Russotto) (01/09/91)
In article <1991Jan8.112500.14143@d.cs.okstate.edu> minich@d.cs.okstate.edu (Robert Minich) writes: >Kent is wrong about (mac<->mac) == (mac<->modem) == (LW|IW<->mac). [Did >that come out right?] The exception is the modem. Serial devices come in >two flavors, Data Terminal Equipment (DTE) and Data Comm. Equ. (DCE). >When wiring DTE<->DCE, the pins labeled Tx (transmit) on both devices >are connected together while DCE<->DCE cables have Tx<->Rx wiring, >eliminating the need for a modem, thus the null-modem cable. Well, actually, the Mac is DTE, if the terms have any standard meaning with 8-pin connectors. There are straight-through 8-pin connectors also. -- Matthew T. Russotto russotto@eng.umd.edu russotto@wam.umd.edu .sig under construction, like the rest of this campus.
woody@ucscb.UCSC.EDU (Bill Woodcock) (01/09/91)
> This is very strange in my opinion. An ImageWriter cable is > a standard serial cable for mac and is intended for > connection of two RS-422 ports. There should be no > difference electrically connecting a mac to mac, mac to > modem, mac to LaserWriter or mac to ImageWriter. > > AppleTalk is software and I don't think software could feel > the difference how you electrically connect the devices in > this case. > > The intention of the LocalTalk box is to let you mix output > signal from different ports and is needed if more than two > LocalTalk equipment are connected. There is no magic in > these boxes. Actually, the main reason for using a LocalTalk transciever box like a Farallon PhoneNet connector is to prevent your SCC chip and potentially your motherboard from being fried by static and higher- than-5v-charges coming in off the port. LocalTalk transcievers by and large do two things: they combine the T+ and T- and R+ and R- onto a single balanced pair, and they provide surge suppression and protection from voltage spikes. -Bill Woodcock BMUG NetAdmin _______________________________________________________________________________ 0000 : 0600 0800 7700 FE00 FF 0 FF8 7F 0 3 00 48 bill.woodcock.iv 0010 : CC00 7C00 0C00 1000 2800 440 8200 40 0020 : C000 4000 8000 C000 C 00 800 80 48 0 9 woody@ucscb.ucsc.edu 0030 : FF00 F000 7F80 CC00 CC 0 7 80 7 80 CC 6 0040 : CC00 7F80 9800 7800 CC00 CC0 CC 0 C 00 2355.virginia.st 0050 : CC00 CC00 FC00 CC00 CC 0 2000 10 0 7 00 C 0 0060 : CC00 CC00 CCC0 4800 2 00 1 00 2 00 48 0 9 berkeley.california 0070 : 4800 2400 1200 1000 2800 4 00 8 00 E0 0080 : 3000 6000 F000 6000 000 60 0 600 C0 0 01C 94709.1315 _______________________________________________________________________________
boortz@sics.se (Kent Boortz) (01/10/91)
by Robert Minich > A straight null-modem cable should do fine for two LocalTalk devices however, > Kent is wrong about (mac<->mac) == (mac<->modem) == (LW|IW<->mac). [Did > that come out right?] The exception is the modem. Serial devices come in > two flavors, Data Terminal Equipment (DTE) and Data Comm. Equ. (DCE). > When wiring DTE<->DCE, the pins labeled Tx (transmit) on both devices > are connected together while DCE<->DCE cables have Tx<->Rx wiring, > eliminating the need for a modem, thus the null-modem cable. IF the modem has an MiniDIN-8 connector, otherwise I can't use an ImageWriter cable, I assume I was right even for mac<->modem. Apple did the right thing leaving this messy RS-232C DTE, DCE... You have never to worry about connecting output to output using two equipment with the Apple MiniDIN-8 standard and cables. I don't even think there is something you can call a NULL-cable in this standard because there is only one cable wiring needed. by Bill Woodcock > Actually, the main reason for using a LocalTalk transciever box > like a Farallon PhoneNet connector is to prevent your SCC chip and > potentially your motherboard from being fried by static and higher- > than-5v-charges coming in off the port. > LocalTalk transcievers by and large do two things: they combine > the T+ and T- and R+ and R- onto a single balanced pair, and they > provide surge suppression and protection from voltage spikes. > -Bill Woodcock > BMUG NetAdmin The transformer inside the LocalTalk transciever box is isolating from DC current but static will be like AC. The transformer will happily give it to your SCC chip. Or is the transformer to small to transfer that much energy or to slow for responding to static? Kent Boortz boortz@sics.se
russotto@eng.umd.edu (Matthew T. Russotto) (01/10/91)
In article <1991Jan9.175029.23835@sics.se> boortz@sics.se (Kent Boortz) writes: > >by Robert Minich > >> A straight null-modem cable should do fine for two LocalTalk devices however, >> Kent is wrong about (mac<->mac) == (mac<->modem) == (LW|IW<->mac). [Did >> that come out right?] The exception is the modem. Serial devices come in >> two flavors, Data Terminal Equipment (DTE) and Data Comm. Equ. (DCE). >> When wiring DTE<->DCE, the pins labeled Tx (transmit) on both devices >> are connected together while DCE<->DCE cables have Tx<->Rx wiring, >> eliminating the need for a modem, thus the null-modem cable. > >IF the modem has an MiniDIN-8 connector, otherwise I can't use an >ImageWriter cable, I assume I was right even for mac<->modem. Apple >did the right thing leaving this messy RS-232C DTE, DCE... You have >never to worry about connecting output to output using two equipment >with the Apple MiniDIN-8 standard and cables. I don't even think >there is something you can call a NULL-cable in this standard because >there is only one cable wiring needed. The only modem I have seen with an 8-pin connector is the Dove Faxmodem--- and they have a wire with a connector that plugs right into the mac. The Imagewriter cable is definitely a null-modem of sorts-- it swaps the TxD/RxD pins. You do need other cable wirings-- extension cables need to be straight through, and the cables I've seen used to connect the ports to AppleTalk in the wall are straight through (though with a change in the boxes in the wall, this need not be the case). -- Matthew T. Russotto russotto@eng.umd.edu russotto@wam.umd.edu .sig under construction, like the rest of this campus.
woody@ucscb.UCSC.EDU (Bill Woodcock) (01/15/91)
>> Actually, the main reason for using a LocalTalk transciever >> box like a Farallon PhoneNet connector is to prevent your >> SCC chip and potentially your motherboard from being fried >> by static and higher-than-5v-charges coming in off the >> printer port. >> LocalTalk transcievers by and large do two things: >> they combine the T+ and T- and R+ and R- onto a single >> balanced pair, and they provide surge suppression and >> protection from voltage spikes. >> >> -Bill Woodcock >> BMUG NetAdmin > The transformer inside the LocalTalk transciever box is > isolating from DC current but static will be like AC. The > transformer will happily give it to your SCC chip. Or is the > transformer to small to transfer that much energy or to slow > for responding to static? > > Kent Boortz > boortz@sics.se The transformer is there to balance and match the impedance of the conductors to that of the network device's serial port. It provides a minimal level of protection from surges and spikes. In addition, there's a spark gap to the serial port's ground, so any voltage over and above what the transformer can take care of will gap across to the ground. This design is the one used by Farallon in both their PhoneNet Connectors and StarConnectors, and is similar to the one used by NeuvoTech in their clone. Some of the other brands don't contain the spark gap. -Bill Woodcock BMUG NetAdmin _______________________________________________________________________________ 0000 : 0600 0800 7700 FE00 FF 0 FF8 7F 0 3 00 48 bill.woodcock.iv 0010 : CC00 7C00 0C00 1000 2800 440 8200 40 0020 : C000 4000 8000 C000 C 00 800 80 48 0 9 woody@ucscb.ucsc.edu 0030 : FF00 F000 7F80 CC00 CC 0 7 80 7 80 CC 6 0040 : CC00 7F80 9800 7800 CC00 CC0 CC 0 C 00 2355.virginia.st 0050 : CC00 CC00 FC00 CC00 CC 0 2000 10 0 7 00 C 0 0060 : CC00 CC00 CCC0 4800 2 00 1 00 2 00 48 0 9 berkeley.california 0070 : 4800 2400 1200 1000 2800 4 00 8 00 E0 0080 : 3000 6000 F000 6000 000 60 0 600 C0 0 01C 94709.1315 _______________________________________________________________________________