[comp.sys.ibm.pc.misc] Setting and reseting DTR through the COM port

rmorris@hubcap.clemson.edu (Robert Morris) (08/07/90)

I need to turn on a box which is hooked to a serial port and is activated by
setting or resetting the DTR.  How does one do this?  I've seen software that   
can so I know it can be done, I just don't know, and can't find out how.
Thanks in advance -----
					Robert Morris
					<RMORRIS@HUBCAP.CLEMSON.EDU>

grege@gold.GVG.TEK.COM (Greg Ebert) (08/07/90)

In article <10038@hubcap.clemson.edu> rmorris@hubcap.clemson.edu (Robert Morris) writes:
>I need to turn on a box which is hooked to a serial port and is activated by
>setting or resetting the DTR.  How does one do this?  I've seen software that   

Your serial port is on either 2F0-2F8, or 3F0-3F8. Use DEBUG to find out. 
Bit 0 of 2F4 (or 3F4) controls the state of DTR. Writing a '0' will put out
-12v on DTR; writing a '1' will put out +12v. Have fun.

drezac@dcsc.dla.mil (Duane L. Rezac) (08/07/90)

From article <10038@hubcap.clemson.edu>, by rmorris@hubcap.clemson.edu (Robert Morris):
> I need to turn on a box which is hooked to a serial port and is activated by
> setting or resetting the DTR.  How does one do this?  I've seen software that   
> can so I know it can be done, I just don't know, and can't find out how.
> Thanks in advance -----
> 					Robert Morris
> 

You can do it with a fossil driver.  check out x00v123h.arc from simtel20. 
It replaces INT 14 with it's own routines, and one of them controls DTR.



Duane L. Rezac



--
Verse of the Hour:
Train up a child in the way he should go: and when he is old, he will not
depart from it.
    Prov. 22:6
-- 
+-----------------------+---------------------------------------------------+
| Duane L. Rezac |These views are my own, and NOT representitive of my place|
| dsacg1!dcscg1!drezac    drezac@dcscg1.dcsc.dla.mil      of Employment.    |
+-----------------------+---------------------------------------------------+

robin@uhccux.uhcc.Hawaii.Edu (Robin Amano) (08/09/90)

In article <10038@hubcap.clemson.edu> rmorris@hubcap.clemson.edu (Robert Morris) writes:
>I need to turn on a box which is hooked to a serial port and is activated by
>setting or resetting the DTR.  How does one do this?  I've seen software that   

What exactly do you need to do?  Are you just toggling DTR on the port or are
you going to communicate through the port?  Most communication software
packages have some kind of hang up command that drops DTR and when you connect
turns it back on.  Yterm will do this with dropcom or the new one 2.1 will
toggle DTR with ^F1, Kermit will do this with ha, Procomm with Alt H.  Not
real sure what you are looking for.
 

rick@wet.UUCP (Rick Rutledge) (08/10/90)

rmorris@hubcap.clemson.edu (Robert Morris) writes:

>I need to turn on a box which is hooked to a serial port and is activated by
>setting or resetting the DTR.  How does one do this?  I've seen software that   
>can so I know it can be done, I just don't know, and can't find out how.
>Thanks in advance -----

Check your local BBS's.  There are PD programs called AT and DTR.  They
operate approximately as follows:

	DTR [COM2] ON|OFF
	AT [modem string]

They both operate from the DOS command line, and like most PD stuff, I think
they are self-documenting or come with a small README file.  I probably have
them here somewhere, but haven't used them in ages.

-- 
------------------------------------------------------------------------------
Rick Rutledge        {hoptoad|ucsfcca|claris}!wet!rick            rick@wet.UUCP
"Voici le secret." dit le renard.  "On ne voit bien qu'avec le coeur.
L'essentiel est invisible aux yeux." -Antoine de St. Exupery, _le Petit Prince_