raise invalidOperatingModeException after serial connection

[yxmagithub]

Dear Development Support Team,
Using the digi-xbee 1.2.0 python library.

after I use the Microcontroller to Serial connection with the SX868 module, I use the GND/DOUT/DIN, which is available to me.

I use the example of senddatasample.py

call the device.open()
it give the following exception,

raise InvalidOperatingModeException("Could not determine operating mode")
I debug the Library, find out that it response with UNKNOWN mode. Most likely it is due to timeout exception, AT response give the timeout exception, than it reports UNKNOWN.

The test environment is the following,

Micro Controller UART (GND/RX/TX) <---> SX868 (GND/DOUT/DIN), baudrate = 9600.
The SX868 is preconfigured to be API mode.

The question about the configuring the SX868 mode,
1.do I have to configure radio module to be local instead of remote? if so, how?
2. How could I write the program to send out / rely with AT command? is it available with Library?

Aaron Ma