-=*>})Charles Gaefke was nattering on to All
   about DosDevIOCtl for COM ports on Wed 23 Oct 96 00:27({<*=-

 CG> I'm _trying_ to write some OS/2 routines (using Watcom 10.6) to
 CG> control  the COM port..  and thus far I'm not having any luck.  The
 CG> documention I have seems to be FAR from user friendly.  I can't even
 
 Yeah, no kidding, eh?
 
 CG> lock the port at a different rate.  :)

You need to relinquish control of the comm port, and then reset it, using
the new locked baud rate.
	   
 CG> Here's my code.. 

 CG> #define INCL_DOSPROCESS
 CG> #define INCL_DOSFILEMGR
 CG> #define INCL_DOSDEVICES
 CG> #include 

 CG> int main(void)
 CG> {
 CG> HFILE  FileHandle;
 CG> ULONG Action;
 CG> ULONG  FileSize, SizeInOut = 0L;
 CG> USHORT FileAttribute = 32;
 CG> ULONG baud=115200;
 CG> APIRET  rc;

 CG> rc = DosOpen("COM2", &FileHandle, &Action, 0L, 0,
0x01, 0x0012,
 CG> 0L); 
 CG> rc = DosDevIOCtl(FileHandle, 0x01, 0x43, &baud, 4L, &FileSize,
 CG> NULL, 0L,  &SizeInOut);

 DCBINFO	dcb ;
 dcb.usWriteTimeout=0 ;		// Set the write timeout
 dcb.usReadTimeout=0 ;		// Set the read timeout
 dcb.fbCtlHndShake=MODE_DTR_CONTROL ;	// Set the hardware control
 dcb.fbFlowReplace=MODE_NULL_STRIPPING | MODE_RTS_HANDSHAKE ;	// Set the
hardware handshake; remove nulls
 dcb.fbTimeout=MODE_NOWAIT_READ_TIMEOUT ;	// Set the timeout features
 dcb.bErrorReplacementChar=0 ;
 dcb.bBreakReplacementChar=0 ;
 dcb.bXONChar

 rc=DosDevIOCtl( FileHandle,
		 IOCTL_ASYNC,
		 ASYNC_SETDCBINFO,
		 &dcb, 
 CG> rc = DosClose(FileHandle);
 CG> 
 CG> return 0;
 CG> }

 CG> Now, my questions being:

 CG> A) what INCL_xxxx lines do I need?  
 
 Just the INCL_DOSPROCESS for the DosDevIOCtl() function.
 
 CG> B) Could someone explain to me the "best" way to open a
COM port for
 CG> reading  and writing?
 
 As you've done above...however, you should also set your device control
 blocks (DCB's).  These set your flow control and your breaking, among
 other things.
 
 CG> C) For DosDevIOCtl, would someone explain, in detail (if at all
 CG> possible) what the ParmList is, and how/when to use it.. what the
 CG> DataArea is, and how/when  to use it, what the ParmLengthMax,
 CG> DataLengthMax, DataLengthInOut, and  ParmLengthInOut are, and how to
 CG> use them.   D) I have two .INF files that give two different
 CG> specifications for the  DosDevIOCtl.  One needs 6 parameters, I
 CG> believe, and the other needs 9.   Unfortunately Watcom complains if I
 CG> only use 6, so I guess I should use 9.   The "6 parameter
one" would be
 CG> for OS/2 2.0 (pre-Warp), correct? 
 
 No.  The 6 parameter one is for OS/2 1.x (16-bit).  However, it's 5
 parameters, not 6.
 
 CG> I'm really lost here, in case you hadn't noticed. :)

 CG> Also, just to make sure, a "word" is an "int"
or "short", correct?
 
 A word is an unsigned short.  Compare with sword.
 
 CG> And a "dword" is a "long", correct?
 
 A dword is an unsigned long.  Compare with sdword.
 
 CG> And a "byte" is a "char", correct?

 A byte is an unsigned char.  Compare with sbyte.
 
 CG> So for function 0x43 in DosDevIOCtl for catagory 1, the ParmList
 CG> is  supposed to contain a "dword" (long baud=xxxxxx) and
a "byte" (char
 CG> divisor=xxxx)?  IF this is the case, how do you pass both of those as
 CG> one  parameter?  Use a structure?
 
 typedef struct _parmlist43 {
	 DWORD	baudRate ;			/* Baud rate */
	 BYTE	divisor ;			/* Divisor */
 } PARMLIST43 ;
 
 PARMLIST43	pl43 ;				/* Declare
						   Instance of
						   Structure */

 CG> If above is correct, then ParmLengthMax would be 5 ("dword" is 4
		 
Oui, monsieur.

 CG> bytes +  "byte" which is 1 byte).  What about DataLengthInOut,
 CG> ParmLengthInOut, and  DataLengthMax?

 CG> And if a port is "locked", do you have to
"unlock" it before you
 CG> can  change the rate, then do you have to "relock" it?

 CG> I appreciate any and all feedback.  What would _really_ help me is
 CG> some  source code with comments telling me exactly what does what. :)


 CG> Thanks..



 CG> C. Gaefke
 CG> cdgaefke{at}sgi.net
 CG> [CDRMAIL Author]

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--- Blue Wave/Max v2.12 OS/2 [NR]