Send explicit data to xbee s1 not working

Setup :
I have 3 xbee s1 modules configured in API mode(changed it from AT mode hoping I would get the right answer but still I get the invalid exception error sometimes) to which a central server xbee communicates.

Problems :
I am planning to send data(string) explicitly to one of the xbees. I found that this can be done using digi-xbee python module. When I code according to the documentation
to send data explicitly I get the error:
Unsupported operating mode AT mode but all my xbees are in API mode. I’m getting this error often even now on my latest execution of the python script similar to the one in the documentation but with 3 xbees instead of 1.

And I also get an error sometimes on this line:

Send explicit data using the remote object.

device.send_expl_data(remote_device, 0xA0, 0xA1, 0x1554, 0xC105, “Hello XBee!”)
There is no mention of what these parameter values mean on the documentation. And when I checked the source code for digi-xbee I found that there is no module named send_expl_data but there is a typo and the module is _send_expl_data. I tried changing that too but still, I’m not able to establish communication between the xbees.

Can someone help me these issues?