FXT009 AT+CFUN=1 and lost the COM port via USB

Dear All,
I’m using a FXT009 under WIN7 managed from c# application.
My problem is that when I try to send the AT command AT+CFUN=1, if i use a USB connection,
the application lose the communication port…instead if i use RS232, the modem answer well.

I tryed to upgrade the last USB Driver but the problem persist.

Does anyone have any ideas?


This is unavoidable :exclamation:

When you reboot the FXT, you also restart its USB stack - which will be seen by Windows as if the FXT were unplugged, and then reconnected.

If you want your C# application to survive this, then you will have to handle the Windows System events which indicate that the USB device has been removed & (re-)inserted.

See: avrfreaks.net/comment/154900 … nt-1549001
And: avrfreaks.net/comment/154902 … nt-1549021