start-up help... which network architecture?

XBee & XBee Gateway XBee - Zigbee
1

Hi all -

We are architecting a new network for outdoor use. We will have a single PC to act as a central collection and distribution point (coordinator?). This system will be located in a nice, cozy, warm environment a few hundred yards (less than 1 mile) away from our main data collection points. The main data collection points will be in a string/star deployment. What I mean by that is the first node (router) will be connected to the coordinator, several end-point units, and additional routers. These additional routers will be connected to seeveral end-points and additional routers, etc, and may be several hundred yards away from the outer routers.

From what I can see on the Digi documentation, this sounds like a traditional Zigbee mesh architecture of possibly a DigiMesh architecture? Can the XBee Pro be used for these architectures? What firmware needs to be loaded? What supervisory programs would be used? Is this what the CoonectPort X4 is used for?

My apologies if these are base questions but there doesn’t seem to be a summary comparison of methodologies other than superficially defined ones.

If anyone has any suggestions on locations for good summary comparisons, I would appreciate it. Any other design suggesstions for this implementation would also be appreciated.

Thanks very much.

Dave

2

It sounds like a mesh environment would be the right way to go, due to the varying distances and type of wireless network architecture. As far as Zigbee mesh vs. DigiMesh, they’re both mesh networks, but a Zigbee mesh might have some devices that would sleep (end nodes), some that stay awake (routers), and one which aggregates the data flow from your wireless network (coordinator).

The ConnectPort X4 is one such coordinator, which could then take the information from your wireless network, perhaps do something with it like pre-process your data via python app, then send it off to some remote location via Ethernet or Cellular IP (in this case the cozy, warm environment).

Another option would be to use a PKG adapter or rf module setup as your coordinator, but you’d then need an application running on a PC connected to your PKG/rf module coordinator to do something with the data coming in from your wireless network.

In the DigiMesh network, the function of end node and router are combined, and both are on a syncronized sleep schedule so all will sleep and wake up simultaneously, at which point data makes its way over the mesh until the nodes go to sleep again. A central aggregating point can still exist.

One determining factor of whether you chose a Zigbee mesh or DigiMesh would be whether your end nodes and routers will have a power source, or whether these will be battery powered. An all-battery-powered network would be better suited for DigiMesh, since all the nodes sleep, whereas if your routers will be powered, Zigbee might be the way to go.

As far as monitoring your wireless network, there are a number of levels from which to chose. At the hardware level, you have the ConnectPort X4 as your coordinator, which has System Information and logging built into it, as well as tracing tools and basic diagnostics available both from Web User Interface or CommandLine. Going a level up, we have the iDigi Dia application, which is a python app created by Digi which you can modify to suit your needs (see http://www.idigi.com/pdf/ds-idigi-dia.pdf). At an even higher level is the iDigi Platform (see http://www.idigi.com).

Hopefully my overview answers some of your questions. There’s also good information here:
http://www.digi.com/technology/drop-in-networking/

3

Excellent! Thanks very much for the info, admin!

I will check the references you’ve listed…

So, from what I understand, if I go with the Zigbee Mesh architecture, I would get something like the XBP24-Z7SIT-004 modules for 2.4GHz, long-range, with RPSMA connectors (we have to use the 2.4GHz rather than 900MHz for peacefully co-existing with an existing 900MHz system)? How do I get the correct firmware to load onto the modules? Is this freeware or does it need to be purchased? Can I use X-CTU to load/flash the firmware onto the modules?

Thanks, again.

Dave

4

The firmware is free and is available through X-CTU. Look for a development board available from Digi.com, Digikey.com, mouser.com, etc. to enable the computer to communicate with the modules. A development board is ~$60 USD but is money well spent. Just make sure you read the manual for the radios first before doing your testing. Some parameters might seem uninportant but may dramatically improve the quality of the network.

5

Thanks very much for the info. That is great news! I’ve actually used the development boards from Maxstream (now Digi) for developing communications links with the XCite 900MHz devices and you are exactly correct… the development board was well worth the money.

I’ve actually already ordered a development kit for the XBee Pro system. Can I use this system to upload the firmware into XBee ZB Modules using X-CTU? Can I put the Zigbee firmware on the XBee Pro modules?

Thanks, again.

Dave

6

The xbee ZB modules already come loaded with the Zigbee firmware. The ZB stands for Zigbee. The firmware may need to be upgraded when you get them in but that can be done with X-CTU.