Page 3 of 4 FirstFirst 1234 LastLast
Results 27 to 39 of 48

Thread: First Bacnet

  1. #27
    Join Date
    Mar 2012
    Location
    San Francisco, CA
    Posts
    14
    This might be a silly question, but are you trying to "WhoIs" across your router with the BBMD turned off? If they are on different subnets, this will not work.

  2. #28
    Join Date
    Aug 2009
    Posts
    2,459
    Quote Originally Posted by Arpoc926 View Post
    This might be a silly question, but are you trying to "WhoIs" across your router with the BBMD turned off? If they are on different subnets, this will not work.
    If you look at the diagram above, it implies that there is but one subnet.

    This drive is set up as a slave, so no "i-am" messages are going to be forthcoming regardless of any subnet issues.

    But while who-is/I-am messages are nice, they are by no means necessary. Any BACnet master or front end can still talk to slaves literally the same way they talk to masters. It's just that scanning tools need to be told to ping manually for them.

    As an example, you could always ping a slave directly. If you know the MAC address (the 0 to 127 number) of the drive you can always ask it a question and see if it responds.

    For slave-finding purposes I choose to ask the device object what its instance is. That way if a unit responds I've already answered the first pertinent question. All other questions can be routed to that MAC address using the device instance it returns.

    For those of you who want to do this manually with VTS or via a local BACnet display, take a look at the MS/TP Wireshark sniffs I've attached below. In them you will see me pinging address 36 for property 75, its device instance. To route to the device object without knowing/specifying the instance, I'm using the wildcard instance which is 0x3FFFFF (or 4194303).

    In the second image you can see the device responding. This response tells me that there is a device at address 36 and it tells me that its device instance is 1036. This is almost all of the info I would have gotten from the device if it had been able to respond with an "I am."

    I realize this may be a bit more advanced than is needed in a thread titled, "First BACnet" but it's good info to get out there in case anyone else wonders how to manually find a slave.

    Attached Images Attached Images   

  3. #29
    Join Date
    Mar 2012
    Location
    San Francisco, CA
    Posts
    14
    Obviously, BACnet, I defer to your expertise. I was concerned that the network architecture might be other than what is represented in the diagram you supplied. If, in fact, the OP had an alternate architecture, but was unaware due to lack of familiarity, reconfiguration of the router to act as a BBMD would both establish connectivity, and diagnose the difference in network architecture from what was expected.

    -http://www.bsubas.com

  4. #30
    Join Date
    Aug 2009
    Posts
    2,459
    I hope you didn't see my post as undermining your comments- they are good thoughts!

    I was relying on post #3 where he stated that the diagram was right. But you are absolutely correct to point out that it might not be exactly that way, even if he thinks it to be!

    I'm hoping someone posts a manual soon. I'm dying to know what "message from master missing" (post #14) means to this drive.

  5. #31
    Join Date
    May 2004
    Location
    SE Pennsylvania
    Posts
    917
    The manual for the BACnet card is vague as hell and the drive manual has no mention of BACnet.

  6. #32
    Join Date
    Feb 2005
    Posts
    1,219
    well simsd says that he has worked with these drives before, so may be he can tell us if this thing is a master or slave, so we can put that fact to bed.

    The pic statement of the card says that it implements the master data layer, unless I am reading it wrong. It ceratinly does not seem to be behaving like a master.

  7. #33
    Join Date
    Dec 2011
    Location
    Winnipeg,Manitoba
    Posts
    33
    I have the manuals from Johnson and Vacon they are both really vague and the BACnet portion is new to them

  8. #34
    Join Date
    Dec 2011
    Location
    Winnipeg,Manitoba
    Posts
    33
    One thing I just noticed is the drawing on the door has the wrong polarity so now I can only talk to the drives with johnsons FX commpro only but still no discovery cuz they are slaves.

  9. #35
    Join Date
    Aug 2009
    Posts
    2,459
    If I understand you correctly, all of your issues have been solved by switching the rs485 polarity? That's great news!

    You can probably take them out of slave mode and put them into master mode, but I don't see any pressing reason to do so. So long as you can read & write to these units your network seems to be healthy and happy.

  10. #36
    Join Date
    Dec 2011
    Location
    Winnipeg,Manitoba
    Posts
    33
    It is a breakthough lol but I talked to the techs at Eaton and they said that these are only slaves, I'm looking at the points now in Fx commpro but I can't get any live readings so I still have some work ahead of me, the Walker head end doesn't provide any tool type to work with , commision or live feed any of the points so I've been trying to use Inneasoft but I think might buy the Chipkin product.

  11. #37
    Join Date
    May 2008
    Posts
    290
    I have just read through this thread and I got caught out with the exact same thing with the modbus card on the Johnson/Eaton VFD. The + and - terminals are back to front.

    I worked it out whils connected directly to it with my laptopo and 485 convertor.

    Dazza

  12. #38
    Join Date
    Sep 2004
    Location
    SoCal
    Posts
    446
    Sorry to hijack your thread but I couldn't resist...

    Ft-10 is polarity insensitive = electrician friendly! Us Lonboys don't have these issues.

    No way would I ever consider an archaic technology such as MS/TP

    Good luck BACknetters,
    lb
    A hundred million nodes - it's a LON story.

  13. #39
    Join Date
    Dec 2006
    Location
    What? Who? Where?
    Posts
    1,693
    Good that you limit yourself, wouldn't want you getting in over your head, keep to the simple polarity insensitive technology it appears a + and - might confuse you.

    kontrol out
    "Open is as open does." - Forrest Gump
    "Can't we all just get a Lon?" - Garry Jack
    "BACnet: integration or interrogation?" - The Janitor
    "Open protocols? You can't handle open protocols!" - Nathan R. Jessup
    “What’s that? Aaa… open protocols? Don’t talk about…. open protocols? Are you kidding me? Open protocols? I just hope we can hardwire an interface!” - Jim Mora http://www.youtube.com/watch?v=U7fjDS0jKiE

Page 3 of 4 FirstFirst 1234 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event