ZigBee Latency

George Krietsepis
George Krietsepis Junior Member
in AMX Technical Discussion
Dear all,
During my first R4/ZigbeeGareway installation I realized that there was a big latency in the zigbee network. In the R4 setup page, we saw a latency value of 65535 which I think this is the largest one and no button pushes could be sent to the NetLinx controller.
To tell the truth there is a WiFi access point (there may be two) in this room which has been set up by our customer network administrator.
I'm afraid that it has something to do with the interference between the two networks.
How can we check that and how can we solve this problem?
Any help will be very useful.
Thanks in advance,
George
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Comments

  • vining
    vining X Member
    If your ZigBee gateway is on channel 25 or 26 you'll be above the WAPs highest RF channel (US) so interferance shouldn't really be an issue unless they are physically on top of one another.

    I've seen that latency before but I never figured out what caused it, possibly to much feedback over loading the Gateway causing it to drop offline. Are you using the feedback module?
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  • George Krietsepis
    George Krietsepis Junior Member
    In fact, I use an Imerge sound server module and it has really too much feedback. Should I remove this instance module for R4? The zigbee gatway uses the channel 26.

    George
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  • vining
    vining X Member
    That's a good place to start. You could elminate everything but the basics in order to evaluate your connection and then once that's known to be good start adding device feedback and control to the R4. In the R4 documentation there's some good reading about do's and don't's to minimize resources. I eleiminate all counter feedback for track or disc time cuz who really cares about that any way.

    Because modifying all your code to accomodate feedback limitations and causing the Gateway to fall offline you should really get and install the R4 feed back module which buffers or queues all channel feedback and strings being sent to the R4 and controls their timing based on a number of factors such as number of hops to the gateway, number of R4 devices etc.

    I think on average you're limited to around 20 messages to the R4's per second. I'm not sure if it makes much difference if it channel, string or level feedback although more than 20 strings per second will most definitely kill it.
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  • a_riot42
    a_riot42 AMX Wizard
    George Krietsepis wrote:
    Dear all,
    During my first R4/ZigbeeGareway installation I realized that there was a big latency in the zigbee network. In the R4 setup page, we saw a latency value of 65535 which I think this is the largest one and no button pushes could be sent to the NetLinx controller.
    To tell the truth there is a WiFi access point (there may be two) in this room which has been set up by our customer network administrator.
    I'm afraid that it has something to do with the interference between the two networks.
    How can we check that and how can we solve this problem?
    Any help will be very useful.
    Thanks in advance,
    George

    It sounds like you are using the old firmware. Update to the new firmware and your latency may disappear. You can also try using the AMX R4 Comm module that will parse feedback to the R4s.
    Paul
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  • George Krietsepis
    George Krietsepis Junior Member
    Thanks a lot for your help but I can not find this AMX R4 module. Is this on the tech support of the AMX site?

    George
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  • Jimweir192
    Jimweir192 Junior Member
    Take a look at technote 864... the module is available to download via the t/n
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  • alexanbo
    alexanbo Junior Member
    vining wrote:
    If your ZigBee gateway is on channel 25 or 26 you'll be above the WAPs highest RF channel (US) so interferance shouldn't really be an issue unless they are physically on top of one another.

    I've seen that latency before but I never figured out what caused it, possibly to much feedback over loading the Gateway causing it to drop offline. Are you using the feedback module?


    Just as a note, I was told never ever to use Channel 25 for the Zigbee remotes by AMX, as they use that channel for some sort of reflection. In fact the option to choose channel 25 is removed in the current firmware.
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  • vining
    vining X Member
    alexanbo wrote:
    I was told never ever to use Channel 25 for the Zigbee remotes by AMX, as they use that channel for some sort of reflection. In fact the option to choose channel 25 is removed in the current firmware.
    I believe that is correct! I recall being very puzzled when going through the set up finding that channel 25 was either greyed out or not listed at all. Given the choice between 25 & 26 it's natural to choose 26 to keep as much distance as possible from the wi-fi stuff.

    Here's a link that I posted when they first started shipping the R4s that discusses zigbee and wifi interfernece that I've been using as a reference.
    http://www.xbow.com/Products/Product_pdf_files/Wireless_pdf/ZigBeeandWiFiInterference.pdf
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