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  1. #1
    Join Date
    Jul 2010
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    Denver, CO
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    435

    Confused BACnet Network Diagnostics

    I am currently commisioning a BACnet network. I have Carrier chillers, Honeywell SmartDrives, and a Grundfos booster pack. They all have BACnet cards. I was importing them into Niagara and got everything imported and all the points imported. The network was find yesterday but today I lost comm to 2 devices and shortly after lost comm to the rest of them. I changed nothing on the network or with the wiring. I can't think of what would cause this therefore I really have no idea where to start my diagnostics. Anyone have any thoughts on this?

  2. #2
    Join Date
    Feb 2007
    Location
    Helena, Montana
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    2,155
    Address conflict? Did you check the Application Directory on the JACE? I had that happen with a "stack error" on BACnet. I had two controllers with the same address.
    Don't worry zombies are looking for brains, you're safe...

  3. #3
    Join Date
    Jul 2010
    Location
    Denver, CO
    Posts
    435
    No errors, no messages in the App Director. It successfully does a discover but the controllers don't even come up in the discovered window anymore.

    But if I try to do a points discover on these devices I get:
    MESSAGE [14:38:19 14-Jun-13 MDT][bacnet.client] TransactionException pinging BacnetDevice {Chiller_2}: Transaction:lockup: invoke ID 1
    MESSAGE [14:38:23 14-Jun-13 MDT][bacnet.client] TransactionException pinging BacnetDevice {Chiller_2}: Transaction:lockup: invoke ID 2
    MESSAGE [14:38:53 14-Jun-13 MDT][bacnet.client] TransactionException pinging BacnetDevice {Chiller_2}: Transaction:lockup: invoke ID 4
    ERROR [14:39:10 14-Jun-13 MDT][bacnet.client] Unable to read the Bacnet object list for BacnetDevice {Chiller_2}
    ERROR [14:39:10 14-Jun-13 MDT][bacnet.client] Unable to learn Bacnet objects in BacnetDevice {Chiller_2}: javax.baja.sys.BajaRuntimeException: Object discovery failed!
    javax.baja.sys.BajaRuntimeException: Object discovery failed!
    at com.tridium.bacnet.job.BBacnetDiscoverJob.run(BBac netDiscoverJob.java)
    at javax.baja.job.BSimpleJob$JobThread.run(BSimpleJob .java)

    Essentially telling me it can't find it

  4. #4
    Join Date
    Jul 2010
    Location
    Denver, CO
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    435
    Time to admit my stupidity

    Loss wire connection where I had to splice the cable, the wires didnt get twisted so one pulled out of the wire nut a little bit

  5. #5
    Join Date
    Mar 2005
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    Pacific Time Zone
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    4,206
    Quote Originally Posted by HuNGRYTeCH View Post
    Time to admit my stupidity
    I hate it when that happens!

    Glad you found it.
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  6. #6
    Join Date
    Oct 2010
    Location
    Baton Rouge, LA
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    1,113
    That is why I don't use wire nuts for communication wires. I prefer using IDCs.
    If you're too "open" minded, your brains will fall out.
    Artificial intelligence is no match for natural stupidity.

  7. #7
    Join Date
    May 2008
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    SouthEast
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    257
    Comm problems can be a pain in the bum.

  8. #8
    Join Date
    Jul 2008
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    1,474
    Quote Originally Posted by HuNGRYTeCH View Post
    Time to admit my stupidity

    Loss wire connection where I had to splice the cable, the wires didnt get twisted so one pulled out of the wire nut a little bit
    Hmm, excessive air-gap
    1 + 1 = 3 ( *** for very large values of 1)

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  9. #9
    Join Date
    Oct 2003
    Location
    Minnesota
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    1,377
    Quote Originally Posted by XcelTech View Post
    That is why I don't use wire nuts for communication wires. I prefer using IDCs.
    Typically the main problem with wire nuts is improper use/installation of them. Not selecting the proper size for the application. Not stripping off adequate length of insulation. Not manually twisting conductors together prior to applying the wire nut. Using the cheap, not spring loaded, wire nuts. Etc.

    That having been said, I'm not pushing the use of wire nuts. Just trying to point out facts.

    The connectors you link to I've used ... no idea how many times ... but its a lot. (Used to work for a phone company.)

    They work and well .... for their intended purpose.

    Which is NOT for applications where one expects high reliability over long periods of time. In the phone company biz, they're used primarily for cheap, fast, residential installation. A use they serve very well.

    IDC's have their issues, also. (1) Small contact area in relation to overall wire size when speaking of any of the larger wire sizes. Can result in mechanical weakness and increased voltage drops at connection. (2) Sometimes you partially cut the conductor, which can lead to noise problems at higher frequencies and/or mechanical failure when after a time the conductor finally breaks. (3) If you don't use the gel filled ones and there is high humidity present connection can corrode over time. Particularly an issue with installations where blade contact area, as compared to wire size, is small. (4) In areas where vibration is an issue, the blades of this type connector have poor memory. Read that to mean they stretch ... apart ... over time. Can result in comm issues in comm applications. (5) If doing troubleshooting and/or repairs, the kind you refer to need to be cut and new one applied. You use of wire that way and can (I've had it happen to me) result in you running out of wire to work with after some time. The reason most phone guy's leave lot of "Service" lenght left during an install.

    Not saying IDC's don't have their place and usage. Just pointing out the cons.

    I come from an industrial control background, and in that field discussions about the best sort of connectors to use for various applications is common.

    Screw terminal connectors have their issues, also. One being that over time they tend to loosen. A common maintenance action/requirement for critical applications is for a tech to routinely check all such connections for tightness.

    Long term, spring loaded connectors tend to be the most reliable over long periods of time. As metal of conductor changes shape, compresses, etc spring tension keeps firm contact made. And have the advantage that you can usually pretty easily remove a conductor without damaging it, having to cut it or re-strip it. Most have some sort of release mechanism.

    I like the Wago spring cage type with release levers. However, the problem is they're relatively expensive, and they pretty big as compared to the alternatives. Bulky, so we're sparing of where we use them.

    We don't use them for comm cables, except rarely. Situations where we'd need to splice comm cables at all ... we avoid. Like the plague. Almost never necessary unless one is just being lazy. Most comm connections are to terminal connectors on controllers, repeaters, routers, etc. I repeat, we try like hell to avoid any other connection/splice in between such devices. When they are actually necessary we use proper size wire nuts (with spring thread insert ... vice the cheap ones), carefully made up, with strain relief provided. But our installers might only do such once a year, On comm cables. They KNOW to avoid it. And will notify the lead controls tech for the project if they do have to do this. To find out if he's agreeable to the exception, or wants them to get rid of it.

    Just some thoughts of mine on the subject.

    Just one call back and comm issue troubleshooting session is enough a void out all the cost saving one might have made by taking shortcuts, using cheap or easy solutions, etc.

    In my experience, when tracking down electrical issues of all sorts, I find that if its a poor, loose, or open connection problem, it's maybe 10 times for likely to be at a screw terminal connection than at a wire nut connection. Given that your installers actually know how to properly use wire nuts.
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  10. #10
    Join Date
    Jul 2010
    Location
    Denver, CO
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    435
    Well since I opened this thread, maybe I can get some diagnostic information from you guys.
    If I am trying to do basic electrical test, can I check my DC voltage between + and -, - and +, and + and - to ground. Will this tell me much, and what would I be looking for?
    Also, if I have a controller or multiple controllers that frequently drop out of the poll, what would be the best way to approach this situation for diagnostics and what would I be looking for?

    osiyo, thanks for your explanation, it definitely made me think of how I approach connectors.

  11. #11
    Join Date
    Jun 2001
    Location
    Michigan
    Posts
    12,077
    stop counting how many times I have had comm loss issues and ignored my better judgement than to check connections. These days, I don't take anything for granted.

  12. #12
    Join Date
    Jun 2001
    Location
    Michigan
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    12,077
    3M Scotchlock gel filled.

  13. #13
    Join Date
    Feb 2005
    Location
    Edmonton, AB Canada
    Posts
    603
    Quote Originally Posted by HuNGRYTeCH View Post
    Well since I opened this thread, maybe I can get some diagnostic information from you guys.
    If I am trying to do basic electrical test, can I check my DC voltage between + and -, - and +, and + and - to ground. Will this tell me much, and what would I be looking for?
    Also, if I have a controller or multiple controllers that frequently drop out of the poll, what would be the best way to approach this situation for diagnostics and what would I be looking for?

    osiyo, thanks for your explanation, it definitely made me think of how I approach connectors.
    Good day HuNGRYTeCH,

    I posted this in another thread...

    Scoping the bus with a Voltmeter will not give you too much information, other than telling you that you have a varying voltage. In order to analyze the digital waveforms you will need an oscilloscope, as this instrument will show you how the voltage signal changes with respect to a time scale (i.e. how the waveforms look electrically... i.e. distorted, induced noise, etc) as well as a the signal's magnitude. This in itself only gives you a piece of the puzzle (the electrical portion), as you will also need a protocol analyzer (or a series of packet captures then fed into Wireshark) in order to investigate the data packets (i.e. content) to/from your particular field device.

    Cheers,

    Sam

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