Attached is a copy of the file that does all the hard work in the usb driver appkvdemoDlg.cpp. You see how much easier to drive it via the OLE interface.
 
 
Software is in visual c++ . But the OLE interface can be driven from any language.
 
 
The system will ride through a USB interface power down, if the system does not power down.  

 
 
The time it takes to send a message to the power supply is 2.5 mS 
 
It takes 100uS to see that the opto link is not there.