XBee: Series1 vs Series2

J^3

After experimenting for the last couple of hours with the XBee series 2 modules I have noticed some properties that I felt where worth mentioning. From what I understand the series 2 modules can be configured to operate in three distinct modes; Coordinator, Router, and End Device. If you have been reading the "Programming and Customizing the Propeller" book these modes are not mentioned. I think that is because the author was using the series 1 modules.(Please correct me if I am mistaken)

In order to set up a network at least one of the modules must be configured as a coordinator, this differs from the examples in the book. I wasn't able to get any communication between two series 2 modules until I had configured one of them as a coordinator. This can be done with the X-CTU software which is a must have(at least for me). Once I had configured one of the modules as a coordinator and left the other in it's default configuration of a router, I was able to get communication between the two devices. I still have a long way to go, and will update what I learn here for others to see. PLEASE, if anyone has experience with the series 2 modules jump in! Also, if someone sees that I am post something incorrect, PLEASE correct me as I am just learning and trying to share what I discover.

So far from what I can tell this is the basic responsibilities of the three different modes:
Coordinator - To setup the network and add other devices to it. Also acts as a router after network has been established.
Router - Must join a network before it can transmit or receive, can also add other devices to network, routes information.
End Device - Most likely to be a sensor(don't know), can not add devices to network, and must transmit and receive through parent device(router/coordinator)

As of right now I am just trying to setup a point to point network, and have been able to receive packets from the router to the coordinator, but not from the coordinator to the router. If any one has any suggestions they would be appreciated, and I will also keep working at it myself. Until I figure more out, have a good night.

J^3

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There are 10 types of people that understand binary, those who do, and those who don't.

Mike Green

The Series 1 modules are set up for point-to-point networking. Each module is set up when initialized to communicate with another specific module (using node/module addresses) or with all modules (broadcast). A module can be reinitialized easily to communicate with another module if needed.

The Series 2 modules are more complicated and do need a Coordinator module to manage the network.

The Series 1 modules are the simplest to set up if all you need are point-to-point connections. There's a utility program that runs on a PC that will do this for you or you can do the initialization with the AT commands using a simple utility running on a Stamp or Propeller or other microcontroller (you'd have to write this yourself). Once the module is configured, the information is stored in an internal flash memory and will take effect when the xBee is powered on. Effectively the Series 1 xBees, once configured, look like a wired link for most purposes (not for downloading programs due to timing issues).

Post Edited (Mike Green) : 7/1/2010 5:16:37 AM GMT

J^3

Thanks for the input Mike,

I went over chapter 5 in PCMP again and found why I was only getting one way communication. The destination address on my coordinator was set to 0, so it would receive what it had sent instead of the other node. I changed the destination address to the physical address of the other node, and now I have point to point communications. For those who don't know, one way to get the address of the device you want to send packets too is read the address of the node using the ATND command. I wasn't able to use the other nodes MY address, it had to be the physical address reported by the ATND command. There is a description of this on page 203-204 in PCMP.

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There are 10 types of people that understand binary, those who do, and those who don't.

Tracy Allen

On series 2, the MY address is read-only and is set by the coordinator.

In series 2, there are 6 different versions of the firmware, three for each of the two modes, transparent (with AT commands) and API (commands embedded in the packets), and within each mode separate firmware for coordinator, router and endPoint. The relative simplicity of series 1 is seen by the fact that there is only one firmware version which covers both transparent and API modes as well as both endPoint/router and should you need it, a coordinator.

EndPoint devices in either series are the only ones that can enter a low power sleep mode, so they are in fact useful for sensors and actuators that might be battery powered. EndPoints can talk directly to one another when both are awake, but it takes a router to relay messages from one sleeping endpoint to another. Routers and the coordinator too can be used for sensors and actuators. Digi makes some nice wall-wart routers that include a couple of sensors that can be addressed in API mode.

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Tracy Allen
www.emesystems.com

himu123

Anyone have experience with the XBee series 2? I like the higher output power (2mw vs 1mw) and lower power consumption vs the original, but am puzzled by the seemingly primitive ZigBee wireless architecture. Needing a dedicated coordinator and end-points (not to mention routers) requires much more infrastructure planning than I am interested in. The original XBee seems to support a non-nonsense adhoc configuration missing from the series 2 (which requires different firmware depending on the usage).

I have need for a solid RF telemetry solution which is usable within my house (fairly large) and adjoining property. The basic XBee looks good with its adhoc support, but I would really like the power/efficiency of the series 2. Appreciate any first-hand feedback. Thanks,


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J^3

Thank you everyone for your posts. I have to retract my earlier statement about the PCMP book not mentioning the three different modes of the devices. After further review of chapter 5 I found that the modes are mentioned. I apologize for any confusion this might have caused to viewers.

himu123. I have only been experimenting with these devices for a little over a day, so take my input as is. If you really want the extended range of the series 2 devices they are not that bad to work with, especially if you use the X-CTU software to configure them. One thing to keep in mind though is with the series 2 modules the first device you configure needs to be a coordinator. Once you do that the rest of the devices can be configured as a router, or end device. I would have at least one router also in order to wake up any sleeping end points as Dr. Allen has mentioned above. I was under the impression that end points could only talk through their parent device though. (coordinator, or router, whoever let them join the network) With as little experience as I have with these devices I was able to get two of them talking in just a few hours.

You also have to remember to change the DL address to the address of the device you want to receive the message unless you use 0xFFFF as the DL which broadcasts to everyone on the network. I believe this is the same in series one though also. Hope this helps.

J^3

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There are 10 types of people that understand binary, those who do, and those who don't.