Ive recently Purchased some Xbee Radios
Model #XNP24BZ7UIT-004 revB
I was hoping to setup a large scale Mesh Network that would incorporate sleeping routers to conserve power. As im finding now this isnt working. After further research it seems this only works with DigiMESH?
Is there something Im missing or is there no way to have Zigbee routers work with sleep mode enabled? and if DigiMesh is a must, what are the limitations?
first of all routers by design don’t sleep. so i assume you mean sleeping endpoints.
I have observed similar behavior. when setting up sleeping endpoints that send data (0x92 packets) they don’t sleep like they should.
Zigbee was designed for cheap hardware, so it doesn’t bother trying to coordinate sleep-clocks. So lets say you tried to have a dozen ‘routers’ wake every 60 second to function as mesh, what you’d find is some would wake up say 0.5 second too soon and other 0.5 seconds too late. In a few hours your routers would all be waking to find themselves the ONLY nodes awake, which isn’t a very interesting mesh
Also keep in mind that ZigBee was designed for home use, so light-switches and power sockets (as example) have lots of power 24-hours a day. The sleeping nodes were assumed to be a small minority of the nodes in the system.
DigiMesh supports sleeping routers in part because they add more accurate clock-hardware (higher material cost, higher power-loss during sleeping), which reduces the sleep-cycle jitter. Plus DigiMesh has nodes ‘sleep/wake’ with small auto-adjust tweaks. So if a node sleeps for 60 seconds and wakes to discover it woke up 0.5 seocnd too soon compared to the sleep coordinator, it sleeps a little longer next time. SO the routers try to keep themselves in the ‘herd’.