On May 16, 2010, at 5:26 PM, Josh Koffman wrote:

> I'd like to use RJ45 connectors to carry the
> RS232 signal. There is a standard for this (EIA-561, mentioned here
> about 25% of the way down the page, but I've seen it elsewhere as
> well) so I feel ok setting it up. I believe that the original intent
> was to use telephone style cable with these RJ45 connectors. What
> would happen if I used straight through CAT5 ethernet cable?


You should be fine.  I've had people complain that the cisco RJ45  
pinout that we designed ended up putting inappropriate signals on  
"pairs" when used with standard telco closet wiring, but those were  
theoretical objections and I don't think there has ever been an actual  
problem.  (since none of the signals are differential, there aren't  
really "Good" signals to pair up, but presumably it would have been  
nice to have RX and TX each paired up with a GND signal rather than  
one of modem signals or each other.)

Note that the EIA-561 standard for RJ45 wiring is pretty uncommon, as  
far as I know.

BillW

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