Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss
COM port vs. RS 232 serial port
28 views
Skip to first unread message
A Aitken
Feb 20, 2012, 2:27:28 AM2/20/12
to
Hi,
Is COM port just a fancy namy for RS 232 serial port?
I suppose the program that connects to these is called a console in
windows and a terminal in unix?
Please correct me if I'm wrong.
Is COM port just a fancy namy for RS 232 serial port?
I suppose the program that connects to these is called a console in
windows and a terminal in unix?
Please correct me if I'm wrong.
A Aitken
Feb 20, 2012, 2:27:38 AM2/20/12
to
Quadibloc
Feb 20, 2012, 5:08:16 PM2/20/12
to
On Feb 20, 12:27 am, A Aitken <andre.ait...@gmail.com> wrote:
> Is COM port just a fancy namy for RS 232 serial port?
Yes, although many peoploe would say it's a *less* fancy name.
> Is COM port just a fancy namy for RS 232 serial port?
John Savard
Mark Thorson
Feb 20, 2012, 7:04:49 PM2/20/12
to
COM ports don't use that part of the standard. I don't
know if COM ports use RS-232 voltage levels.
Joe Pfeiffer
Feb 21, 2012, 12:36:49 AM2/21/12
to
use what any reasonable person would regard as the RS-232 standard
(though the normal way to get pedantic about it is to insist on
referring to it as TIA-232, which has been its name since ...
checking ... 1997). They do follow the standard voltage levels and use
the DE-9 pinout specified in EIA-574.
See http://www.interfacebus.com/Design_Connector_RS232.html
Message has been deleted
ChrisQ
Feb 26, 2012, 12:59:10 PM2/26/12
to
On 02/21/12 12:01, Morten Reistad wrote:
> Moving signals around to connect a DTE to a DTE (null modem
> cable) is a somewhat black art, because various vendors have
> different interpretation of signals. The standard only
> got proper state diagrams late in V.24 history; RS-232C
> never had them. And DCE-DCE (null terminal cable) is high
> black art, requring experienced whiches.
>
> The last one was never meant to be possible.
>
> -- mrr
>
It can be a black art, but for 25 pin D, linking 5,6,8 and 20
at both ends, then connect pin 7 to Pin 7, Pin 2 to 3 and Pin
3 to 2, end to end, usually gets the job done, unless you need
hardware flow control...
Regards,
Chris
> Moving signals around to connect a DTE to a DTE (null modem
> cable) is a somewhat black art, because various vendors have
> different interpretation of signals. The standard only
> got proper state diagrams late in V.24 history; RS-232C
> never had them. And DCE-DCE (null terminal cable) is high
> black art, requring experienced whiches.
>
> The last one was never meant to be possible.
>
> -- mrr
>
It can be a black art, but for 25 pin D, linking 5,6,8 and 20
at both ends, then connect pin 7 to Pin 7, Pin 2 to 3 and Pin
3 to 2, end to end, usually gets the job done, unless you need
hardware flow control...
Regards,
Chris
Message has been deleted
Robert Myers
May 19, 2012, 12:31:57 PM5/19/12
to
On 2/27/2012 7:06 AM, Morten Reistad wrote:
> In article<jidrtb$l44$1...@speranza.aioe.org>,
> The whole handshake is supposed to start with setting DTE, pin
> 20 high by the DTE. Until that happens, everything else is low.
> So you need to get hold of a high signal somwehere when linking
> two dces.
>
> For dte to dte, you link 7 to 7, 20 to 8+6, 4/5 crossed, and 2/3
> crossed, 24 to local 15 and remote 17, and vice versa for clock;
> thereby simulating the modem handshake.
>
The only cable I ever built was a null modem cable, and, as I recall,
the entire magic consisted in crossing a pair of wires. I won't say
that everything went smoothly all the time, but I did manage to transfer
the data I needed to transfer. If I had had this level of detailed
advice, I probably would have been discouraged from trying. ;-)
Robert.
> In article<jidrtb$l44$1...@speranza.aioe.org>,
> 20 high by the DTE. Until that happens, everything else is low.
> So you need to get hold of a high signal somwehere when linking
> two dces.
>
> For dte to dte, you link 7 to 7, 20 to 8+6, 4/5 crossed, and 2/3
> crossed, 24 to local 15 and remote 17, and vice versa for clock;
> thereby simulating the modem handshake.
>
The only cable I ever built was a null modem cable, and, as I recall,
the entire magic consisted in crossing a pair of wires. I won't say
that everything went smoothly all the time, but I did manage to transfer
the data I needed to transfer. If I had had this level of detailed
advice, I probably would have been discouraged from trying. ;-)
Robert.
0 new messages