How to get multi-threaded topology using xbee zb?

Question

I use some xbee (s2) modules with zb glass to evaluate the grid network. Therefore, you need to create an environment with several spasmodic changes. The problem is that the firmware processes the association for itself, and there is no way deeper into the stack, as the api provides. In order to force the data path without violating the routing mechanism, I tried to measure, I had to put them out of their reach. To get only the next transition to an association is not so simple. I used the lowest power level of the output signal, but the distance for the test setup is large, and the characteristics of the RF environment are not defined.

So my question is, does anyone have any experience with this issue?

Regards, Toby

Answer 1

I do not think that this is possible with the help of software and coordinators / routers. You can change the Node ATNJ ( ATNJ ) to force the new router to join a specific router (disable Node Join on all but one node), but this will only affect the connection. After connecting to the network, the router will detect that other nodes are within range.

You could do this with sleepy end devices. You can use the ATNJ trick to force the end device to join a single router, and it will always send its messages to that router. But you will not get that many hop senders go to the parent router, which sends to the target parent router, which sends to the target end device.

You will probably need to physically limit the range of the radio stations in order to make them jump, as shown in the video that you connected with the Digi K-Node test equipment with a network of more than 1000 radio stations. They put radios in boxes with RF protection and use wired antenna connections with software-controlled attenuators to connect the modules to each other.

If you have XBee modules with a U.fl or RPSMA connector and do not connect an antenna, this should significantly reduce the range of the module. Otherwise, using a wire whip or a built-in PCB antenna, you need to put each radio in a box that attenuates the signal. Perhaps someone else can offer advice on materials that will reduce the signal range without completely blocking it.

Answer 2

ZigBee nodes attempt to automatically form an Ad-Hoc network. That is why they join the network with the strongest connection (best network coverage) available at that moment. These modules are designed in such a way that you do not need to worry much about establishing a reliable connection. They will solve network problems most of the time.

What you want to do somehow makes a different situation. You want to create a specific topology to get a few jumps. This will not be a normal nod behavior. But you can get what you want with some AT commands.

The specified "NJ" command should work for you. This command blocks connections after a certain time (in seconds). Let's think about a simple ZigBee network with three nodes: one coordinator, one router, and one end device. Turn on the coordinator with "NJ" set, say, two minutes. Then quickly turn on the router so that it can communicate with the Coordinator during these two minutes. After these two minutes, the coordinator will be blocked and will not accept any more connections. At this point, you can start the End-Device, which must be associated with the router. This way, you will see that the messages between the end device and the coordinator go through the router as you wish.

You can get a large network by applying this idea several times, without having to play with modular antennas. You can manage AT parameters remotely (i.e. from a computer connected to the Coordinator), so you can use some code that will help you initialize the network.