I tried a three-node AT network with two routers and one coordinator. Loaded the firmware fresh on all nodes, and it works as expected. By changing the coordinator's DH/DL it can send data to either router. No Arduinos were involved, the XBees were just plugged into adapters (I use Adafruit's
) and connected via FTDI to three copies of X-CTU running on the PC. So your plan should
A couple things to watch for. First, "association" does not guarantee the ability to communicate! A router can be associated to a network, then the entire rest of the network can be taken down, and the router will still be associated and the LED will still blink. Check the Operating PAN ID (OP) and Operating 16-bit PAN ID (OI). All nodes should have the same OP, and all nodes should also have the same OI (OP and OI do not have the same values, but if ID > 0, then OP will equal ID). If this is not the case, force the module to disassociate with an ATDA command.
Secondly, I do get the occasional bad firmware load, which is why I suggested reloading firmware earlier. I've never figured out why this happens, it could well be a personal problem but I just don't know. In fact, when testing the three node setup earlier, I had one router that appeared not to associate in that the LED did not blink, but in checking the OP and OI parameters, it looked OK, and it would in fact communicate but only in one direction! It took about three tries reloading firmware before I got it right. So take that with a grain of salt, YMMV, but it might be worth a try.
Let me know what happens.