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Multiple Xbees communicating with Multiple XBees

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I am trying to work with a project where multiple devices will be communicating with each other over XBees. For example, device 1 may be sending data two device 2 and 3 over XBee. The problem is that communication can happen at any time and between anyone. This means that device 2 may "possibly" send data at the same time, resulting in device 3 getting two messages, while device 1 and 2 are supposed to be receiving a message while sending.

Is this even a possibility with XBee? If so, would it require something like synchronization of communication one the devices, or is there a way to configure the XBee devices to do this? I am mainly using XBee Pro's, but I can switch to anything if needed.
asked Jan 9, 2014 in IEEE 802.15.4 by LoveTesting New to the Community (0 points)
recategorized Apr 14, 2014 by tuxembb

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1 Answer

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Hello LoveTesting,

This should be possible to achieve, assuming you are using Series 2 (ZigBee). I would use API mode instead of AT, so the application knows which node sent which message every time.

Best regards,

answered Jan 10, 2014 by spastor Veteran of the Digi Community (403 points)
I am currently using XBee XSC (not the S3B but the S3 MCQ-XBEEXSC).  I know they are not ZigBee, but I am not sure exactly what type they are.

I would like to use API mode, and I have seen in various places and manuals that mine has API mode, but I cannot seem to find out how to turn it on.  Using X-CTU, there is no option for my device.  Currently, my message that I send includes a from and to component, as well as the data.  If this message is preserved given my below concerns in AT mode, I would be okay, but I know API mode is better.

So is the reason why ZigBee can handle it due to the Mesh Networking it employs.  The big things I am concerned about are

1) What type of message does device 3 get if device 1 and 2 talk to it at the exact same time?  Two separate messages, or one that is thrown away?
2) Can a device send and receive at the same time?
3) I know all data is stored on an internal buffer and needs to be parsed quickly.  Is there any information on how large that buffer is?

I have a few assumptions for these questions, however, I would like to get some confirmations.

Thanks for your time.
A 900HP was suggested for me to use.  For a system communicating between multiple devices (with multiple xbees), would a DigiMesh or a Point to MultiPoint system be more reasonable?