[comp.sys.ibm.pc.hardware] COM port "shuts off"

peter@kentrox.uucp (Peter Uchytil) (03/13/91)

I'm having a problem with PC com ports, and I'm wondering if anyone
else has seen this particular sort of thing (silly question?).  We
don't have any PC gurus here unfortunately.  

Ok, what's going on is I have a program that is receiving data on COM1
and COM2 simultaneously.  When the amount of incoming data is large,
one of the COM ports will "shut off".  That is, the program can't talk to
it and it won't talk to the outside world.  The affected COM port is
always the same on a given machine, but varies from machine to machine 
(on my Compaq it is always COM2, but on my IBM XT it is always COM1).
If I reinitialize the COM port, everything's happy again.  I have noticed
this behavior from 1200 to 9600 baud.  If data is coming in on only one
COM port, there is no problem.  It is only when large amounts of data
are coming in on both COM ports simultaneously.

So, is this a known problem on PCs?  Is there something obvious that I'm
overlooking like I'm not handling some RS232 lines properly?  Right
now the only solution I can see is to periodically reinitialize the COM
ports.  I'd rather not do this because I never know when data is going to
be coming in.

Any and all thoughts would be appreciated!

Pete
--
Peter Uchytil
Kentrox Industries, Inc.
uunet!kentrox!peter