[PLUG] RS232 wiring help

[Don Buchholz]

Jeme,

I think I'd start with this simple 2-wire config first,
how it works:

     TxD  <->  RxD
     RxD  <->  TxD

I know it's better to have the signal ground (GND) line,
but if it's not available ....
... another possibility is to solder the ground to metal
surround the end (perimeter) of the DB-9 connector ....

Just my $.02 -- I'm *not* a EE.

- Don



Jeme A Brelin wrote:
> Hi.
> 
> I've got to build a cable for pulling a serial console up on this old
> ethernet switch.
> 
> Now, I've got the pin diagram for the RJ45 on the switch, but I'm not sure
> how to wire them to the DB9 for my PC.
> 
> The RJ45 diagram looks like this:
> 1  Transmit Data (XMT)
> 2  Data Carrier Detect (DCD)
> 3  Data Set Ready (DSR)
> 4  Receive Data (RCV)
> 5  Signal Ground (GND)
> 6  Data Terminal Ready (DTR)
> 7  Request To Send (RTS)
> 8  Clear To Send (CTS)
> 
> Now, my understand of RS232 on DB9 is as follows:
> 1  Data Carrier Detect (DTD)
> 2  Receive Data (RxD)
> 3  Transmit Data (TxD)
> 4  Data Terminal Ready (DTR)
> 6  Data Set Ready (DSR)
> 7  Request To Send (RTS)
> 8  Clear To Send (CTS)
> 
> So what's 5 and where does the signal ground go?
> 
> Can someone give me a quick chart to show which pins on the RJ45 go to
> which pins on the DB9?  I'm not in a position to get another DB9, so I've
> really got one shot at this or waste a whole day until I can get another
> connector and get back here.
> 
> I'd make a stab at it intuitively and see what happens, but I'd rather
> check with the old-school wiring experts I know sit on this list.
> 
> Thanks.
> J.