For all users migrating from 1.X to 3.0 API :

Ainit time, after preliminary inits (okFrontPanelDLL_LoadLib & okUsbFrontPanel_Construct() )
you MUST call okUsbFrontPanel_OpenBySerial before attemting any USB comm.

For Jake : maybe you could update the migration doc…:smiley:

Actually, this has been a requirement in all versions of the API. It should be clear in the FrontPanel User’s Manual, but we’ll go back and check that it is.