Hi, I tried several options, but none of them gives a solution :

• Default port baud rate (device manager-properties) of the COM1-port = 9600.  Starting the software with bd=9600 : problem remains
• Setting the COM1 port BD to 4800 (default bd of the controller) : same problem
• ...

The strange thing is : with the laptop I can make a connection with the controller although the port bd (9600) is different than the controller bd (4800).  So the laptop can change this without blocking the software

Just an addition : I can modify the controller by using your ASPM program, that works perfectly, so I made an order note to by a licence.  Why the controller software causes the com port to block will maybe remain a mystery...

Dear all,

I have a strange problem : I have a building controller that I can configure using a DOS-software.
On a laptop, everything works fine, I can make connection
On a desktop, it does not work
Hardware setting are the same on both : baud 4800, data bits 8, stop bits 1, Parity none, Flow control Xon/Xoff

I used the 'spy' function to detect data traffic.  When the program starts, with the laptop, COM1 is opened, initialization runs with baud 4800 and there is connection; with the desktop, COM1 is opened and initialization runs suddenly with baud 1200.  And then the software blocks.  Since that's the only difference, I guess this is the cause.

Does anyone have an idea what causes this problem and how to solve it?  In attachment you'll find a printout of both the desktop and the laptop 'spy' results.

Many thanks in advance!