Intermittent connection failure


We have a network of about 25 nodes running in an indoor environment. the nodes are programmed to wake-up from hibernation every 30 mins and transmit data to a logging server.

The network has one Coordinator and 3 router nodes which are always powered. when the network is switched on it works for about two days with no problem whats so ever. but after that time about 6 nodes randomly stops communications. furthermore we found out that they have a problem to be associated at wake-up or subsequent wake-ups.

I’d be pleased if anyone can shed some light on this.

Thanks & Rgds,


I m not sure about the sleeping parameters of the devices. Create an Online Support Request at the following link, , digi experts will help you to solve your problem.
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I’ve just finished installing a bigger network (30 end-devices, 2 routers) with 12 devices working in sleep mode (sleep times range from 1 to 5 minutes). Except for one node that constantly losses connection all work fine for days (network is running for more than one month now).

Days ago I read in this same forum a post from lynnl talking about how important is setting, in both routers and coordinator, the max time an end-device remains in the router/coordinator child tables.

The essence is that, if this time is shorter than the end-device inter-wake periods, routers/coordinator delete from their child tables sleeping devices since they think that devices has roamed (or in general, that devices have left the network). When the end-device wakes and send data, routers/coordinator dont find a table entry for them and they drop the data.

The way of solving it is stating the right value for SN/SP in the ROUTERS and COORDINATOR. In these devices, the max. time a child is kept in the parent table is three times the value (SN*SP)/100 (in seconds).

So for instance, if your end-devices wake each 30 minutes, you must set a parent table timeout (I repeat, in routers and coordinator) higher than 30 minutes, ie, (SN*SP)/100 must be higher than 600 (since 600 seconds = 10 minutes and parent table timeout is 3 times that value, ie, 30 minutes).

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So make sure you are using the latest 2xA7 firmware.

Also make sure you have the same Sn?SP in all the routers (ao any potential parent), plus use the JV=1 setting in routers so worst-case they ‘demand’ to find a coordinator after the router reboots. Without this, trying to ‘move’ the coordinator to a new channel is nearly impossible since the routers remain forever on the old channel.

Be aware that some older Xbee firmware have ‘bugs’. For example the 2x70 series in end-devices at times caused sleeping node to fail to reconnect AFTER the parent was rebooted. Also, the 2xA0 had join issues where even a ‘router’ might think it is associated to a coordinator, but the coordinator would never report it as joined.