First you have to download and install the usb-driver for the logger-device. You can use the universal one from the chip-manufacturer: SiLabs. The second step is a little bit complicated, but has to be done only once. First open the "Terminal" in "Application/Utilities". Then enter - as administrator - in that terminal (press return or enter after each line): sudo mkdir /var/lock sudo chmod 777 /var/lock The first line creates the directory "/var/lock" and the second makes it read/writeable for all users. In the future releases for bt747 (2.x) this step is not longer needed. In the last step, you get BT747 to your comptuer. Go to the webinstall-page and try or install BT747. Or if you like to have all files on your local computer, go to the BT747-Sourceforge-page and download the current stable version. Unzip the content and run the desktop-version by clicking on „bt747_macosX_j2se.command“. The correct port should be detected automaticaly by using "USB (for Linux, Mac)" - please connect and turn on the logger before you start BT747.