Update of /cvsroot/com0com/com0com
In directory sc8-pr-cvs4.sourceforge.net:/tmp/cvs-serv11876
Modified Files:
ReadMe.txt
Log Message:
Added FAQ about receive buffer overrun
Index: ReadMe.txt
===================================================================
RCS file: /cvsroot/com0com/com0com/ReadMe.txt,v
retrieving revision 1.8
retrieving revision 1.9
diff -C2 -d -r1.8 -r1.9
*** ReadMe.txt 5 Dec 2005 10:43:19 -0000 1.8
--- ReadMe.txt 28 Jun 2006 13:59:03 -0000 1.9
***************
*** 9,13 ****
Windows. You can create an unlimited number of virtual COM port
pairs and use any pair to connect one application to another.
! Each COM port pair provides two COM ports with names starting
at CNCA0 and CNCB0. The output to one port is the input from other
port and vice versa.
--- 9,13 ----
Windows. You can create an unlimited number of virtual COM port
pairs and use any pair to connect one application to another.
! Each COM port pair provides two COM ports with default names starting
at CNCA0 and CNCB0. The output to one port is the input from other
port and vice versa.
***************
*** 111,112 ****
--- 111,127 ----
A. You must prefix name with the special characters "\\.\". Try to open the port
with CreateFile("\\\\.\\CNCA0", ...).
+
+ Q. My application hangs during its startup when it sends anything to one paired
+ COM port. The only way to unhang it is to start HyperTerminal, which is connected
+ to the other paired COM port. I didn't have this problem with physical serial
+ ports.
+ A. Your application can hang because receive buffer overrun is disabled by
+ default. You can fix the problem by enabling receive buffer overrun for the
+ receiving port. Also, to prevent some flow control issues you need to enable
+ baud rate emulation for the sending port. So, if your application use port CNCA0
+ and other paired port is CNCB0, then add the following to the registry:
+
+ [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\com0com\Parameters\CNCB0]
+ "EmuOverrun"=dword:FFFFFFFF
+ [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\com0com\Parameters\CNCA0]
+ "EmuBR"=dword:FFFFFFFF
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