Voltage, Scanning and Impedance

Discussion in 'C-Bus Wired Hardware' started by GlenF, Jul 2, 2018.

  1. GlenF

    GlenF

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    Hi all,

    Just hoping for some advice on a small issues I have been having. I have a pretty large setup with 63 items on the network. It all works fine except when I scan the network on toolkit it almost always misses items and sometimes as many as 20. The provided power is 1800 vs a requirement for ~1200 and the network impedance is 1160 so it all seems ok. However, when I run the diagnostics, the voltage of many items is as low as 25V.

    I have a few questions I would appreciate thoughts on:

    1. I did have a physical network burden plugged in. I have tried it with this removed and installed and it does not seem to make any difference to the network or the scanning. Am I best to leave it out or plugged in?

    2. Would it help if I added another power source on the network.

    3. Is there any other reason why I would be missing items on the scan.


    Thanks in advance.

    Glen
     
    GlenF, Jul 2, 2018
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  2. GlenF

    Wonkey

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    Hi Glen
    You have not given the forum a lot of info to help resolve this issue.
    Things like
    how old is the install
    has it ever scanned correctly
    Which units are missing or is it random.
    Version of toolkit
    Type of interface used

    Ideas to help with the little info provided
    Break the network down into a smaller network and see if the smaller network scans.
    Check all units that may have a software enabled burden if you can, scan and open, them check the status tab.
    You mentioned diagnostics I presume you mean diagnostic utility (https://www.clipsal.com/Trade/Support/Software)
    If you are using this there are a couple of under used features called Traffic analyser and reliability test
    consider using those to help. the help file explains how to use them.

    I may be worth checking the wiring connections as poor connections cause this type of problem
    Water ingress is also a consideration, if you have units or terminations that may be in an area that could get wet, or been exposed to bad weather.
    C-Bus works operates well even with poor connections etc, but when you come to scan it then the issues show up due to the higher communications demand on the network.
    Colin
     
    Wonkey, Jul 2, 2018
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  3. GlenF

    znelbok

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    The reason for the low voltage could be because of how the network is physically laid out.

    If the power supplies are at one end of the network then all the devices at the other end will see a higher voltage drop and that could be why you are seeing 25V. Distributing the power supplies along the network ensure that the voltage drop is kept to a minimum.

    Not an answer to your problem, but hopefully an explanation on why you are seeing what you are seeing.
     
    znelbok, Jul 3, 2018
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  4. GlenF

    GlenF

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    Thanks Wonkey and Znelbok.

    A bit more information: The install is about 12 months old and I have had issues scanning from the beginning. It is interfaced through a CNI2. I am using the latest version of toolkit and the items that get missed are pretty random.

    I will experiment with moving the power supply around to see if it helps.
     
    GlenF, Jul 3, 2018
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  5. GlenF

    Wonkey

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    OK
    So when you have moved your PSU check the voltage again if possible with a multimeter and compare with toolkits results, the guidance is from Clipsal is no more than 10v volt drop across the whole network.
    As you have mentioned its been like this from new I would be thinking its an installation issue,
    Could you do a simple test with your multi meter measure between C-Bus positive and Earth and then C-Bus Negative and earth. The results should be similar within a few volts of each measurement.
    If you find that one measurement is at C-Bus voltage and the other zero then you have a conductor that is shorted to earth. If so start looking in the key inputs for cable twisted around the fixing screws
     
    Wonkey, Jul 3, 2018
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  6. GlenF

    GlenF

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    Thanks, will work my way through it next week
     
    GlenF, Jul 3, 2018
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  7. GlenF

    Shiney2512

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    I’d be checking if there are too many software burdens and clocks have been selected In your devices, Maximum of 3 clocks per network and 1 burden (if required), and network voltages are above 21 volts (25v is ok, and shouldn’t cause too many issues).

    As mentioned above, try and find the fault by breaking down the network until scans properly , start by removing the field devices first, scan the network and then build the network up until the fault appears - if possible use another interface to eliminate a dodgy cni.
     
    Shiney2512, Jul 3, 2018
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  8. GlenF

    GlenF

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    Thanks Shiney, will do
     
    GlenF, Jul 4, 2018
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