[time-nuts] Z3805 utility, Was: AW: (no subject)

Jeff Hook jeffhook at comcast.net
Mon May 24 01:15:58 UTC 2010

Does your "plain" serial cable have 25pin on one end and 9pin on the other?
If so, it shoud be 2-3 and 3-2 (because of DB9 toDB25 conversion)
If its 2-2 and 3-3 its a null modem cable (this is what you want)

This is not true if its 9 pin to 9 pin or 25 pin to 25 pin cable
"standard" serial cables are 2-2 and 3-3
Null modems are  2-3 and 3-2


> Jeff,
> I just measured one of my " plain serial" cables, it's 2-2 and 3-3.  Now 
> I'm really confused!!!
> "TX" and "RX" have the same pin numbers, so a DCE to DTE needs 2&3 
> swapped.  Does that mean a DCE to DTE needs a null model, or is that the 
> other way around?????
> I always feel like an amateur when playing with RS-232.....
> Bob

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