Route Contention?

Using XBee 900 modules configured for sleepy meshing, we’re preparing for installation with basic requirement is that we have at least two hops in a grid of separated sensors. It appears that we’re not getting the desired two hops. The configuration involves a node which is sufficiently far from the coordinator to be out of range. If a node is placed roughly midway between the node and the coordinator, things work as expected But if two routers are in range of the node, then messages get through with difficulty, if at all. So routing is possible through any of the two routers, but not at the same time. One idea is that a three-hop route is created, which is failing to work.

Should odd behaviour like this happen with xbee networks?

steve d.

I would suggest looking at your SP. ST, NH and BH commands. Make sure they are sufficiently long enough to get the data over multiple hops.

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Thanks for your reply! Our sleep/wake cycle is very generous, 10 sec awake, 10 sec asleep. NH is 7 (the default) so the timeouts should be fine, and BH is 0, which the docs assure me means unlimited broadcast radius.

I managed to construct a situation where I had a node A going through a router R to the coordinator, but a node B just outside R’s range was unable to reconnect through A, even though it was only thirty metres away (we easily get sixty metres with these units)

Check the TO command. You may need to adjust it to 0xC0.

There’s no TO command on this device (XP09-DM, Digimesh 900); the registers controlling the network are HP,RR,MT, BH, MR, NH and NN.

You are correct. That product does not support the TO command. Try setting the BH to 7 which would match your NH value.

Thanks, that does seem to help! I successfully managed a three-hop connection. (To get more, I would need a larger campus ;))