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Xbee delayed after around 8 packets

0 votes
Hi !

I'm trying to send data in AT mode between 2 Xbee pro S2B.
5 Xbee belong to the network : 1 coordinator and 4 routers.

I send "+B0000108C2FF;" and i wait an acknowledgement. When the exchange is good, it's around 80 ms.

Now my problem:
After around 8 calls I get my first big delay with an amount of 2-6 seconds. Then I have some fast responses and then again some long delays :

Something goes wrong, it's so regular !

Experiment :

73 ms
68 ms
70 ms
75 ms
80 ms
73 ms
77 ms
3032 ms
4199 ms
84 ms
76 ms
75 ms
73 ms
79 ms
87 ms
76 ms
2880 ms
4263 ms
73 ms
75 ms
68 ms
67 ms
89 ms
73 ms
76 ms
2545 ms
4200 ms
78 ms
82 ms
78 ms
77 ms
86 ms
82 ms
77 ms
2493 ms
4203 ms

What could be the reason for this big delays? Has anyone an idea? and why is it regular?
I first thought this is because of the xbee sleepmode but X-CTU says the sleepmode is inactive or Packetization Timeout but no, I always tryied ...

Sorry for my English !!

Thanks you !!

Nicolas
asked Feb 6, 2018 in ZigBee PRO Featureset (and legacy ZNet 2.5) by Nicolas_4 New to the Community (0 points)

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1 Answer

0 votes
no there is nothing wrong. What is going on is that you are sending data in Broadcast mode. When using this mode, you must wait between each transmission to allow the packets to be re-broadcasted by the other routers.

This is per the Zigbee and IEEE standards.
answered Feb 6, 2018 by mvut Veteran of the Digi Community (14,676 points)
Thanks you for your answer,

but I have to broadcast ... I want to make a star network in AT mode with one central router which broadcast each others.

I tryied to reduce "re-broadcast" with Broadcast Radius parameter but, no change about this delay.
So what you really wanted was a Point to multi-point network with all in range of the Multi-point base.  Zigbee will not allow you to send broadcast packets out on a continuous basis with short intervals.  For that kind of network, you need to have an IEEE 802.15.4  or other Point to multi-point (Non Mesh) network.
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