802.15.4 - One coordinator and 2 endpoints, second endpoint not answering everytime

I’ve got one coordinator :
MY : 0x00
DH : 0x00
DL : 0xFF
CE : 0x01
A2 : 0x01

And 2 endpoints :
MY : 0x01 and 0x02
DH : 0x00
DL : 0xFF
CE : 0x00
A1 : 0x01

Periodically the coordinator emits one frame and sequencially each endpoint answers.

After each startup, i’ve got some issues :
the second endpoints never replies. After some time (> 30s) it replies.

Does anybody have any idee of the problem ?


Are you using Sleep modes? If you use Unicast addressing instead of Broadcast addressing, what happens?

After many tries I reduced the radio power and the problem went out.
XBeePro modules were too close for these powers.