I try Synchronized Cyclic Sleep with my XB8-DM (XBee 865/868LP 80K, firmware 8072).
SM = 8
S0 = 6
And when the Xbee wakup or go to sleep I receive :
7E 00 02 8A FF 76
A "Modem Status" frame with Status = FF (Unknown status) when I wait for Status = 0x0B or 0x0C.
Did I miss something?