CC2650EM-5XD-RD: coordinator sending leave request to end device ?

Which packet number in your sniffer log do you see leave request?

please refer packet no . 316899 ,316923 ,316945

Does device 0x186c join correctly into coordinator? Which packet number I can check it joined correctly?

if you check the packet no. 314350 zed (0x186C) it was in the network and also sending report command.
till packet no. 314379 it was also sending mac frames.
then at packet no 314650 to 314667 it tried rejoining automatically .
and after some time at packet no- 316899,316923,316945 ZC sends leave request.

I don't see device 0x186c does rejoin in packet no 314650 to 314667. I see coordinator sends node descriptor and simple descriptor requests in packet no 314650 to 314667. Since your device 0x186c is not polling, it cannot get any ACK. What is polling rate of your ZED and what Z-Stack version do you use on cc2538-cc2592 emk as coordinator(znp) ?

Polling rate is defined in f8wconfig.cfg. I see your CC2650ZED doesn't do polling in your sniffer log. Since you use Z-Stack 3.0 coordinator, it will age out the device which doesn't polling for a long time. When the aged out device tries to send message to coordinator, the device won't be on association list and coordinator will ask device to leave to do rejoin.

-DREJOIN_POLL_RATE=440

-DMAX_POLL_FAILURE_RETRIES=2

-DAPSC_ACK_WAIT_DURATION_POLLED=3000

so these are the values defined in f8wconfig.cfg.

POLL rate is defined by

/* The number of milliseconds to wait between data request polls to the coordinator. */
-DPOLL_RATE=1000

should i modify it?

The default polling rate is 1000 ms but I don't see your device 0x186c does polling every 1000 ms.

ZED 0x186c is deployed away from the sniffer therefore sniffer is not capturing these packets.is that possible?

What do you mean is that possible?