MSP430F5529: Not able to write the commands on launchpad

Part Number:MSP430F5529

Team,

Can you please help with my customer's question below:

I am configuring MSP430F5529 Launchpad as a CDC device  and trying to communicate it  from Ubuntu terminal.

I have loaded the  TI stack on the microcontroller and successfully communicated using PuTTY from Ubuntu terminal.

Next , I want to use libUSB for communication with the micro  instead of PuTTY.

I am able to open the serial port using libusb but not able to write the commands.

Thanks

Viktorija