I have a SE network using a coordinator and 2 end devices.
I configured the sleep commands like this:
SM - 4
SN - 1
SP - 03E8 (10sec - sleep period)
ST - 4E20 (20sec - time to join to the network)
When I use the XCTU, everything goes all right. I can send API commands to the end device and when he wakes he replies.
The problem is: when I connect the end device to the Arduino ( to program the response), I send the same commands and he dont wake up.
That is part of the initialization of the port. If you do not know how to perform that function, then I would suggest checking either the documentation for the processor or one of the Support forums dedicated to the Arduino processor as they will have that information.