Hi Sachin,
Generally when MC7455 module is connected to Linux machine, check the module detected or not. i.e. lsusb or lsusb –t
Once the module is detected, then provide this command to get the USB ports info : ls /dev/ttyU*
Any one of the USB port will be your AT port and provide that port number in Minicom. So that you can provide the AT commands.
For further any queries , Please contact your Technical support in SWI to provide you the solution.
Thanks and Regards,
Rex.