Re: Serial Connection

[Stephen Powell <zlinuxman@wowway.com>]

On Sun, 27 Mar 2011 19:30:49 -0400 (EDT), owens@netptc.net wrote:
> On Sun, 27 Mar 2011 14:41:37 -0400 (EDT, Stephen Powell wrote:
>> 
>> That's true. But a properly-wired cross-over cable or null modem 
>> not only crosses over TD and RD but also crosses over DTR and DSR 
>> and also crosses over RTS and CTS. Ground, of course, is wired 
>> to Ground. CD is normally tied to DSR on the same side of the 
>> interface (on both sides). RI is usually left unconnected. 
>> 
>> See, for example, 
>> 
>>    http://en.wikipedia.org/wiki/File:D9_Null_Modem_Wiring.png 
> 
> Yes Stephen that's the "traditional approach".  Unfortunately
> there are at least half-a dozen non-standard configurations
> (e.g. permanent RTS, connecting DSR to DTR) which drive RS-232
> people nuts.  I agree that the place to start is with your
> traditional cable or with a null modem adaptor (essentially a
> black box that does all the interconnections for you, allowing
> straight through cables from either side to the boxes) but beware
> this may not work in all situations.

I agree.  Special situations may require special wiring.  As I
said in another post, the devil is in the details.

-- 
  .''`.     Stephen Powell    
 : :'  :
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   `-