Does xbee s1 and s2 differences support the zibgee protocol?
I don't understand this question.
Series 1 XBees and Series 2 XBees both support the Zigbee protocol, the same way.
I want to set up a network consisting of s1 module, 2 coordinators and 25 endpoints.
If s1 means Series 1, then you can dream on. Series 1 models do not talk to Series 2 models. You can NOT have 2 coordinators in a mesh network. Series 1 models form point to point networks, so there is no need for a coordinator.
if there is another endpoint in the coverage area then it will wait to pass the communication.
The only way that an end point will know if there is another end point that the coordinator can see is if the coordinator tells it that. The coordinator won't volunteer that information. It will have to be asked. The end point will have to do the asking, which means that it will NOT wait until there is no other end point in the area, because it can not know that there is another end point in the area.