XBee S2 problem

Hello friends,

I am using two XBee S2 module for my own project. But I can’t figure out why there is a delay when the router received data from a coordinator.

Here is the configuration for my two XBee modules.


Modem: XB24-ZB
Function set: Zigbee coordinator AT version 208C
PAN ID: 27

The other:

Modem: XB24-ZB
Function set: Zigbee Router AT version 228C
PAN ID: 27

When the router transmit data to the coordinator, it works well. The coordinator could receive it and display the data in the Serial monitor.
But when I want to transmit data from a coordinator to a router, the Serial monitor couldn’t get the data at the same time. Maybe several seconds later, it displayed.

I don’t know what cause the delay.
Any suggestions will be helpful.
Thanks a lot.


I always use API on coordinator, so don’t have any experience with an AT-mode coordinator.

My first guess is the coordinator is always doing route discovery, whereas the router is remembering that it can talk directly to the coordinator (they use a different algorithm). The route-discovery involves a broadcast (much like an IP ‘ARP’) asking who knows how to reach the IEEE MAC address. This takes up to 5 second to complete.

I don’t know how to speed up the process.