Make sure that the correct drivers have been installed. Uninstall and reinstall the Breathe-Link software making sure that you agree with the terms and conditions, and tick the agree box. Click OK when asked to install drivers. In some instance where the battery of the POWERbreathe K-Series device is very low, the drivers fail to detect the POWERbreathe. In this instance connect the POWERbreathe K-Series device as normal and briefly push the ON button of the POWERbreathe. The associated drivers will then be detected and normal connection procedures should be applied. Make sure the POWERbreathe K-Series device is switched OFF before attempting to connect with the Breathe-Link Software.
Make sure no other device is connected to the PC/MAC that draws more then 500amps.
If the problem still persists contact supplier of the device.