Re: RS232 pin.4 and pin.8

From: boki (bokiteam_at_ms21.hinet.net)
Date: 10/09/04 

Date: 8 Oct 2004 20:09:33 -0700

Dear Chris,
           I got it, thank you very much. :)

Best regards,
Boki.
cfoley1064@aol.com (CFoley1064) wrote in message news:<20041007134736.05051.00004569@mb-m24.aol.com>...
> >Subject: RS232 pin.4 and pin.8
> >From: "Boki" bokiteam@ms21.hinet.net
> >Date: 10/7/2004 12:13 PM Central Daylight Time
> >Message-id: <ck3tge$mag$1@netnews.hinet.net>
> >
> >Dear All,
> > The pin.4 and pin.8 are not Tx or Rx of RS232, why I can
> >trigger RS232 directly by short them ?
> >
> >Best regards,
> >Boki.
>
> I'm assuming you're talking about a DB-9 connector. Pin 4 is Data Terminal
> Ready (DTR), and pin 8 is Clear To Send (CTS). The software you're using is
> apparently telling the other side the Data Terminal is Ready, and when you
> short the two, your software is noticing that the other side is sending that
> it's Clear To Send.
>
> You've got to back up the truck a bit here. First, on a hardware level, all
> you're talking about is I/O port locations. You can read pin status by
> bit-banging the ports. The trick is to get the UART to do the job of sending
> and receiving serial transmissions.
>
> Go to the library and borrow or buy a copy of "Serial Port Complete" by Jan
> Axelson. There's a wealth of information in there for newbies on RS-232,
> including software and drivers for BASIC, C, and Visual Basic. It's a bargain
> if you're doing any hardware interface or programming with serial ports. If
> you're in a hurry, go to the website for the book
>
> http://www.lvr.com/serport.htm
>
> and read some of the links. You'll learn what you need to know to do what you
> want.
>
> If all you want to do is read logic level of a few lines, you should be able to
> do that quite easily. It should be especially easy if you use DOS with C on an
> older PC. Also, the RS-232 port is pretty much goofproof. It's very difficult
> to smoke it (although not imposible). However, if you're interfacing to +5V/0V
> logic, it's a lot more likely you'll smoke some of that stuff.
>
> Do a little reading first. You'll have a more enjoyable ride if you know
> something about what you're doing.
>
> Good luck
> Chris

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