Can I Connect 1000 End devices to just one coordinator?

XBee & XBee Gateway XBee - Zigbee
1

How many end devices XBee ZB serie 2 could I connect to 1 Coordiantor?
I am starting a wireless sensor network using just one coordinator, 125 routers and 1000 end devices. They are all Xbee ZB serie 2.

I wondering about if is this possible, if Im going to have problem with the traffic the coordinator can support. I dont even know if this amount of devices can be use in the same network. If not, which is the limit of devices.

2

wow!
It is the experiment which seems to be very interesting.

Since 12 maximums have the number of end device which can accommodate one router, it is likely to be necessary to arrange router and end device well.

In the network built once, coordinator and router are mutually connected in peer to peer.
Therefore, since it is especially coordinator, a burden cannot be heavy.

However, cautions may be necessity that broadcast overflows.

It wishes to succeed.

3

Hi there, thx for ur replay,
The thing is i want to put 1 xbee on each door of store in a mall to send me if the temperature on the store is ok, so i will need a lot of end diveces, and routers to get that data from each Xbee End Device to one coordinator, so i need to know if this can be posible.

Thanks in advance.

4

Hi jacoboconde!

Chobichan is correct. If you are using the XBee Series 2 ZB modules you’ll need a ratio of 1 Router node for every 12 End Devices. The reason for this is if a message is sent from the Coordinator to and End Device and the End Device is sleeping, then somebody in the mesh network has to be awake in order to receive the message and hold onto the message until the End Device wake up.

Even still there is some special setup you’ll need to get the network to scale: http://www.digi.com/wiki/developer/index.php/Large_ZigBee_Networks_and_Source_Routing

If you do end up using the XBee Series 2 ZB modules, you can use a product like this to add router nodes into your network:

http://www.digi.com/products/wireless-modems-peripherals/wireless-range-extenders-peripherals/xbee-wall-router#overview

You may want to consider DigiMesh as an alternativ: http://www.digi.com/technology/digimesh/

DigiMesh allows for sleeping routers and can scale out to very large networks. The way it works is everybody goes to sleep and wakes up at the same time. You’ll need XBee Series 1 modules to use DigiMesh.

How often do you need to send the temperature from each sensor? Which sensor will you use? Where will you send the information? Are you going to use a gateway?

5

With that many nodes, you will need to:

  1. be very careful to avoid broadcasts (which is why Jordan suggests the ‘Source Routing’).
  2. be very careful of when data is sent - so understand your app and make sure you have lots of excess band-width since it will be near impossible to keep the nodes nicely spaced out.
  3. avoid any ‘start-up’ problem - imagine your 1000 nodes are powered, and a power outage recovery causes all 1000 to try to send at once … big problem.
  4. remember the 12-to-1 ratio is theoretical. You don’t control which end-device joins which parent, so you cannot prevent 10 nodes which (as example) could join Parent A or B from joining parent B and stranding end-devices which CANNOT see parent A but only B. So you are probably safer with an 8-to-1 ratio (which 125 routers to 1000 end-devices) would be.

Personally, I think you’ll be happier (unless you buy & use an RF sniffer/analyzer) to split your system into smaller chunks - say 250 per ‘Ethernet-gateway/coordinator’, give them different PAN ID and even different channel/frequencies. Less eggs in 1 basket. Digi has customer with 1000 devices per mesh, but they spend copious amounts of time tuning their protocols to avoid broadcasts and band-width saturation.