🚀 go-pugleaf

Hi,


I am relatively new to UNIX serial I/O at the application level.  I am 
currently porting a fairly involved UNIX (Apollo SYSV based) product (Many
processes, SYSV IPC w/ message queues).  I am having some problems
doing serial Input/Output using the read(2) and write(2) system calls.


System
------
Open Desktop 1.0.1 and Open Desktop 1.1.1
i386 with 25Mhz 
20 MB RAM
Standard COM1: and COM2:
		- Using the non-flow control devices tty1a and tty2a
		- XON and XOFF not used
Ethernet (wd8013E)
Super VGA (Tecmar VGA/AD)
Adaptec SCSI and 300MB Hard Drive


The system is communicating at 9600 baud with a fast hardware device.  I have
heard rumors that ODT may have problems with 9600 baud modems.  If this
is true, a reply from SCO would be appreciated.


Symptom(s)
----------
write(2) is not returning a -1 but is also not sending all of the data
I ask it to.  The next call to write(2) never succeeds in sending data 
(verified with data line monitor).

Possible Causes
---------------
	- Serial overflow (Docs. indicate I/O can be lost, is hanging also
			   a symptom).
	- Multiple writers to same COM: port.
	- SCO Serial driver bug
	- Some sort of flow control is being used even though it is disabled.


Code in question
----------------

 alarm(30);
  if ( (rc = write(fd, &buf->pad[VTK_PAD_SIZE-1], size)) != size)
    {
      /* log the error and return */
      if (rc == -1) {
        fprintf(stderr,"\n\rvtko: Write Failure\n\r");
        perror("vtko");
      } else {  <-------- rc == 0, errno == 0
        fprintf(stderr,
                "\n\rvtko: Tried to write %d bytes, only sent %d bytes\n",
                size, rc);
      } /* else */
      alarm(0);
      uel_log(vtk_my_name, VTK_COM_WRITE_FAIL, ZERO, params);
      return;
    } /* if */
  alarm(0);




Any possible help and/or suggestions and/or authoritative answers from SCO
would be appreciated.

Reply via net, fax,  and/or phone.

							Jerold A. Abramson

							Software Engineer
							Voicetek Corp.

							@ addr: jaa@world
							! addr: ...!uunet!world

							FAX: 1 (508) 250-9378
							Voice: 1 (508) 250-7957