FreeBasic interfacing causes UNO to restart when opening COM port

Hello all. I am trying to interface the PC to Arduino Uno using FreeBasic ( The UNO is connected via USB to the computer (Windows Vista 64bit), and I am using the virtual COM port (COM3). I am using the following command in FreeBasic to open the com port:

open com "COM3:9600,N,8,1,cs0,ds0,cd0,rs" FOR BINARY AS #1

(I have also tried some variations of this command, with different parameters)

I have loaded a very simple sketch on the Uno which listens to the serial data, and if an 'A' is received, the Pin 13 LED is turned on. If a 'B' is received, the LED is turned off.

I am attempting to use FreeBasic to send these characters to the Uno.

Every time the FreeBasic application executes, I can watch the Uno reboot as the com port is opened. If I add a 'sleep 2000' command after the Open command, I can then send the 'A' and 'B' characters to turn the LED on and off. I realize this has something to do with the way FreeBasic handles the port, and the DTR line.

However: if I open a command prompt and execute the command

echo A>com3

The device does NOT reboot, but instead immediately turns on the LED as it is supposed to.

Anyone have any ideas on how to prevent the FreeBasic port initialization routine from rebooting the Uno each time it opens the connection?

Thanks very much for any assistance!


The arduino is known to reset COM ports are opened, there are many posts on this forum e.g. -,64956.0.html -

Think you need to tweak with "cs0,ds0,cd0,rs" part of the open command, but no guarantees