Help choosing the right module

XBee & XBee Gateway XBee - Zigbee
#1

I want use the ZigBee (open protocol) for connect several modules in a home of 200 m2 on three floors. What series and power I need?
I saw that znet modules can be converted to zb, with x-ctu (I don’t know if all znet modules can).
I want to connect them all like digimesh does, and so I will set them in router mode, and then with a PIC, change the operation mode (router or end point) with the Sleep Mode option, if a node doesn’t need to be router, decreasing the power consumption. All the modules will be connect to a power supply, no batteries.

  1. Is it possible?
  2. What series and power I need?

Thanks!

#2

Update: Oops… wrong article link.

Perhaps you should read this first? http://www.digi.com/pdf/wp_untanglingthemesh.pdf
The document will help you to decide which series to go for before deciding that you want to embark on ZB

#3

Perhaps you should read this first? http://www.digi.com/hottag.jsp?ht=/pdf/wp_zigbee.pdf
The document will help you to decide which series to go for before deciding that you want to embark on ZB

I already knew the article, but doesn’t answer at my questions…

#4

Hi,

You can have better solution, Please refer the following link, “http://www.digi.com/support/kbase/kbaseresultdetl.jsp?id=3025” and download the Conversion kit, it may be helpfull for you.

Xbee Series2 modules will support ZB or ZNet.

ZB does not work like Digi Mesh, there are specific roles that have to be accomplished in the mesh network.
a) There must be a coordinator to choose the channel, allow joining, set encryption, etc. It doesn’t have to always be around, but it must be present to start the network.
b) routers have to be always powered so that they can maintain adaptive route tables.
c) end nodes don’t do anything unique to routers other than have the ability to sleep in exchange for lower power consumption. end nodes don’t maintain a route table, routers do.

In DigiMesh there is no real route table in most cases, the data is just transferred and there is a sense of directionality to it.

Hope this helps!

Regards!
Kavya

#5

All the modules have a power supply, I don’t have power problem. I want only optimize consumption, setting as router the minimum possible end points.

I don’t know what RF power I need, if 1mw or 10mw (non PRO or PRO), for an 3 floors house, putting the coordinator on the middle floor.

#6

No one can answer your questions - depends on the type of floor, how much metal in the walls/floors, and so on.

Just guessing, aiming for 25% PRO routers, 50% non-PRO routers and 25% end-device should work well. There is no reason to use end-device unless they are battery.

Then scatter the PRO routers around the outer edge of your house to offer mesh diversity.

#7

Thanks, I would change from router to end-device when is possible only to reduce power consumption, even if is plugged in to wall.

#8

An end-device which is full powered will take more power than a router - unless it sleeps.

A router can sit queitly and say nothing, merely have it’s RF receive active.

An end-device sits there and chatters (sends an RF beacon) every 100msec forever to its parent looking for data. So you’d only save power if the end-device (for example) slept, waking every 15 seconds only.

#9

This is an interesting information, thanks a lot!

#10

It is a side-effect of supporting sleeping. Imagine your "end-device’ is a temperature sensor waking every 20 seconds, so sleeping for 19.75 seconds & awake for 250msec. At any time you wish to send it a message, it is probably asleep. So it wastes everyone’s resources (even RF bandwidth) to try and talk to it because 98% of the time it hears/recv’s nothing.

Instead the router/parent holds the message as proxy, and always lets the end-device/child poll for it when awake. The child wakes, takes it’s sonsor reading, asks the parent if it’s holding a message for it, possibly sends a new data sample and goes back to sleep.

So if you power an end-device full time, by default (the PO setting = 0), the child asks the parent every 100msec “Got work for me?”, “Got work for me?”, “Got work for me?”, “Got work for me?”, …

#11

How the digimesh protocol solves this problem? It has sleep, and less power consumption than router in zigbee protocol.

#12

I’ve corrected the link at the second thread of this topic. You should read that first. Gives you a general overview of the type of radio you would need for your project.
Also if you are still deciding between DigiMesh and Zigbee read here first http://www.digi.com/pdf/wp_zigbeevsdigimesh.pdf

#13

DigiMesh tends to take more power while sleeping, because they run a more accurate clock hardware. Today, the ZigBee are the lowest power Xbee we have.

So with 10 sleeping Zigbee nodes, if you ask them to wake in 1 hour, there will be a high error rate (a few minutes skew?)

The DigiMesh modules will have far less skew, but the cost is a higher sleeping current.