Issue with multiple Xbees talking in transparent mode

Using Arduino Networking, Protocols, and Devices
#1

Hi enthusiasts :D ,

I am using three Xbees which communicate with each other. One of them is a coordinator (in broadcast mode) and the other two are the end devices. The Xbee have been programmed using AT commands through X-CTU and are set to talk in the transparent mode. Initially I had only one Xbee as an end device and the data reception was fine. However, when the second Xbee was added, both Xbees still started receiving data but in an interrupted manner (i.e. the incoming data was cutting off and then reconnecting continuously).

I had two high gain antennas (one 20 dbi and one 9 dbi) on the end device Xbees and they were placed closed to each other. Could that be causing the issue? The issue would stop once one of the Xbees was disconnected.

In general, is there a limit on how many Xbee end devices I can connect with a coordinator which is broadcasting? Any ideas what was causing the problem and how this can be prevented?

Many thanks in advanced :D

#2

Any ideas what was causing the problem and how this can be prevented?

In API mode, each packet identifies which device sent it. I can't imagine how you think you can have one coordinator (think kindergarten teacher) with a collection of senders (think kindergarteners) shouting all at once, and make any sense of the responses.

API mode makes the senders at least identify themselves, so you have a snowball's chance of making sense of the data.

#3

Hi and thanks for your reply. :)

I can't imagine how you think you can have one coordinator (think kindergarten teacher) with a collection of senders (think kindergarteners) shouting all at once, and make any sense of the responses.

Based on what you say I think my understanding is incorrect. :disappointed_relieved: I thought that the co-ordinator Xbee was the kindergarten teacher and the end-device Xbees were the kindergarteners waiting and listening to any broadcasted data. I did not think of the end-device Xbees as a collection of senders, but actually receivers.

Considereng that I set the co-ordinator to broadcasting mode, I was hoping that it will talk to any number of end-devices which happen to be in the vicinity of its broadcast and receive the radio waves sent from it.

#4

Hi PaulS,

I did some extra research and found a similar situation to mine to which you had provided a really good solution:

The way to handle the paradox is to have the master use broadcast mode to request data from a specific Arduino. The master XBee broadcasts a request for data ("Hey, Joe, talk to me"). All the XBees get the request, and pass it on to the Arduinos. Only one Arduino knows that it is "Joe", so only it prepares a reply, and passes it to its XBee to send, directed to the Master's DL. The other Arduinos know that they are not "Joe", so they do nothing about the incoming request.

But, then I realised that in my case I have multiple Arduinos asking for data from one module rather than a master requesting data from a specific Arduino. Sigh :disappointed_relieved: . Is what I have quoted what along the lines of what you told me previously? If that is the case, I do not think it is applicable to me as I want multiple xbees to receive data from a master xbee simultaneously. Do you think there is a way around this? Maybe using a Wifi module to create an access point so multiple devices can receive the data that one xbee end device receives?

Cheers!! :)

#5