zigbee packetization

Projects Networking, Protocols, and Devices
1

I have two Zigbee XBee Pro S2 modules.

One is a Coordinator and the other is an End Device.

Data sent from the Coordinator arrives at the End Device more or less immediately.

Date send from the End Device to the Coordinator only arrives every 30 seconds, unless there has been prior data sent from the Coordinator.

In other words if there is a command response format, comms is realtime. If the End Device wants to send an unsolicited message it will only do so every 30 seconds.

Is this some setting in the modem or something to do with the polling rate?

I am sure this is just a configuration issue somewhere?

Any suggestions appreciated.

2

Is this some setting in the modem or something to do with the polling rate?

Or something in the code on one end or the other.

I am sure this is just a configuration issue somewhere?

How DID you configure the XBees? If you followed digi's advice, the results you are observing are exactly what I would expect.

By default, coordinators are in broadcast mode. Broadcast communication is very low priority.

Configure the coordinator XBee to talk to ONE other XBee, or use Andrew Rapp's XBee library which manages that in code.

Using mesh network models for point to point is a waste of money.

3

Hi Paul, thanks for responding.

The Xbee's are being used basically as point to point at the moment. Yes a waste of money but hey, I just get given the hardware to work with!

Configuration wise, I used the X-CTU tool. Nothing in code.

As they are just being used for a simple point to point, I haven't gone digging into the whole configuration yet.

I'll get back to you with the settings I have.

So it's expected that data from the End Device is only delivered out of the Coordinator every 30 seconds?

4

So here are my settings for the Coordinator:

XBP24-ZB_20A7.mxi
80
0
261
20A7
0
[A]ID=0
[A]SC=1FFE
[A]SD=3
[A]ZS=0
[A]NJ=FF
[A]DH=13A200
[A]DL=40C32662
[A]NI=
[A]NH=1E
[A]BH=0
[A]AR=FF
[A]DD=30000
[A]NT=3C
[A]NO=0
[A]CR=3
[A]SE=E8
[A]DE=E8
[A]CI=11
[A]PM=1
[A]EE=0
[A]EO=0
[A]BD=3
[A]NB=0
[A]SB=0
[A]RO=3
[A]D7=1
[A]D6=0
[A]CT=64
[A]GT=3E8
[A]CC=2B
[A]SP=20
[A]SN=1
[A]D0=1
[A]D1=0
[A]D2=0
[A]D3=0
[A]D4=0
[A]D5=1
[A]P0=1
[A]P1=0
[A]P2=0
[A]PR=1FFF
[A]LT=0
[A]RP=28
[A]DO=1
[A]IR=0
[A]IC=0
[A]V+=0

And here are my settings for the End Device:

XBP24-ZB_28A7.mxi
80
0
261
28A7
0
[A]ID=0
[A]SC=3FFF
[A]SD=3
[A]ZS=0
[A]NJ=FF
[A]JN=0
[A]DH=0
[A]DL=0
[A]NI=
[A]NH=1E
[A]BH=0
[A]DD=30000
[A]NT=3C
[A]NO=0
[A]CR=3
[A]SE=E8
[A]DE=E8
[A]CI=11
[A]PM=1
[A]EE=0
[A]EO=0
[A]BD=3
[A]NB=0
[A]SB=0
[A]RO=3
[A]D7=1
[A]D6=0
[A]CT=64
[A]GT=3E8
[A]CC=2B
[A]SM=4
[A]ST=1388
[A]SP=20
[A]SN=1
[A]SO=0
[A]PO=0
[A]D0=1
[A]D1=0
[A]D2=0
[A]D3=0
[A]D4=0
[A]D5=1
[A]P0=1
[A]P1=0
[A]P2=0
[A]PR=1FFF
[A]LT=0
[A]RP=28
[A]DO=1

My problem is that the End Device will only send data to the Coordinator if the Coordinator has just sent something to it. End Devices seem not to be able to just transmit back to the Coordinator whenever they want. (or at least not with these settings)

Any clues what's not set right?

I thought that the only configuration I need to do was to set one end as a Coordinator and the other as an End Device, then put the Serial number of the End Device as the Destination address in the Coordinator and that's it?

Any help appreciated!

5

And I found that this issue only occurs with Series 2 Pro Xbee as my old Series 2 units work fine.

I did a test a found that as soon as transmissions from the End Device to the Coordinator are more than 5 seconds apart, it stops sending anything.

I guess this is some sleep mode issue?

UPDATE!

Yes it was a sleep issue. Set ST to 8000 and it works as required.