henry@hplabs.HP.COM@utzoo.UUCP (02/05/87)
> I am very disturbed about one message I read. The person proposed to > use modular telephone connectors for connecting RS-232 serial lines. > I think this is a BAD IDEA. Modular plugs were developed to connect > telephones and only telephones, and that is how they should be used lest > some bozo should happen to plug an RS-232 cable into a telephone jack > and fry the serial card with -48V when it wants +/-12V or, worse yet, > cause damage to our wonderful Public Switched Telephone Network. As various people have pointed out, modular plugs and jacks are already extensively used for RS232 connections. (Incidentally, one of the more notable outfits using them this way is AT&T -- I believe that all or most of the 3B line use modular jacks on their serial interfaces.) It should not be forgotten that this sort of problem is already everywhere. One can make a good case that it was a bad idea to start using the "D" connectors for anything that isn't RS232-compatible, but that battle is long lost. Microcomputer parallel ports commonly use 25-pin D connectors nowadays. The POWER feed from the Sun-3/180 serial mux to its distribution panel uses a nine-pin D connector, just like the ones used for serial lines on a number of computers now. It is rumored that the connector for the IBM PC token-ring network is identical to the one for the IBM PC video output. And so on. The moral of the story is that you have to stop and think before plugging a plug into a jack, regardless. Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,decvax,pyramid}!utzoo!henry
grr@seismo.CSS.GOV@cbmvax.UUCP (02/12/87)
In article <8702092006.AA21253@ucbvax.Berkeley.EDU> henry@hplabs.HP.COM@utzoo.UUCP writes: > >It should not be forgotten that this sort of problem is already everywhere. >One can make a good case that it was a bad idea to start using the "D" >connectors for anything that isn't RS232-compatible, but that battle is >long lost. It should also be pointed out that AT&T has long used 'RS232' i.e. DB25 style connectors, for the *Telephone* line connections on their traditional modems and other incompatible devices such as auto-dialers. It's always been a think before you plug situation...