Subj : DosRead - access denied?
To   : Francois Thunus
From : Vitus Jensen
Date : Tue Jun 13 2000 06:50 pm

Moin Francois,

13.06.00 07:27, Francois Thunus wrote a message to Vitus Jensen:

 VJ>> Could someone name any reason why a DosRead() from a serial port
 VJ>> will return error code 5 (access denied) ?  It's listed as
 VJ>> possible error code but i would connect it with DosOpen().

 FT> The only reason I could imagine is that some other program is
 FT> accessing the port at the same time and that for some reason OS/2
 FT> cannot handle the priorities between the two programs fighting
 FT> for the com port.

I'm doing DosOpen() with OPEN_SHARE_DENYREADWRITE so there *should* be no other 
process acessing the port.  Theoretically.


 FT> If you did not have access to the com port at all (for example my
 FT> dos boxes by default do not have access to all com ports), the
 FT> DosOpen() would fail first, so you would never reach the
 FT> DosRead() stage (if my understanding is correct).

That's the same understanding I have about this matter.  But in real life we 
have:
 1. error 5 is listed in DosRead() docu and
 2. there is at least one machine where it is returned.


 FT> It would be helpful if the person who has the problem can give
 FT> you a list of all other programs running at the same time,
 FT> specially those susceptible of accessing the com port.

In the meantime he fixed the error in his driver w/o running the testprogram.  
So I'm happy with the result even if I wonder.  But it's an idea to ask him for 
a pstat /C result.  We will see what this gives...



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Great!

C-x C-s,
    Vitus

--- Sqed/rexx 489:
 * Origin: See the Future; See OS/2.  Be the Future; Run OS/2. (2:2474/424.1)

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