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Thread: Max Masters

  1. #14
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    nice brief doc from Carrier... http://www.xpedio.carrier.com/idc/gr...808-417-01.pdf

    MM looks like a way to not waste time looking for nodes that arent there...
    APDU looks like how long to wait before deciding to move on because on no answer...
    Max INFO frames seems like a limit on how much crap an MSTP device is allowed to talk before being compelled to pass the token.

    Heres the thing ...Like every polling or master-slave or token passing bus, the physical medium must be solid or the whole system is going to fall down and not work
    assuming the physical is correct and the comms is robust it makes me wonder WHY arent things like MM set automatically by the network?

    Adding a new MSTP device should beautomatic in my opinion too. Considering that there is already a net-wide unique devID... should be able to hook it on the bus...everybody goes 'whoa dudes...new device here" and comms moves on...in fact why have a MAC at all?? why not shunt around the whole devID its only 2 or 3 bytes bigger than the MAC...ah, but of course because somebody in the committee needs a way to ID a device on the bus with a DIP switch ... so MSTP needs just one more little address space.
    1 + 1 = 3 ( *** for very large values of 1)

    ...everybody wants a box of chocolates and long stemmed rose

  2. #15
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    Quote Originally Posted by mechmike2 View Post
    I was under the assumption that the max masters setting referred to the physical number of devices on a network but as I sit here after wasting a day trying to get a bacnet network communicating it occurred to me that the max master setting may refer to the max MSTP address on the network which would explain why I can't discover some devices and have iffy comm. throughout my 5 networks. Can someone confirm or deny. I'm not looking to start another lon vs. bacnet debate.
    What kind of controllers are you using? I just recently had a similar problem and it ended up being controller specific...


    Im like a mushroom, they keep me in the dark and feed me crap.

  3. #16
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    The issues addressed here with MS/TP here are issues of lack of understanding of basic networking in the field. Most of these issues have nothing to do with MS/TP but are issues of RS-485 and token networks. Most of the parameters discussed should be set to defaults which are typical for your style networks and layouts. The reason I have to say your style is because everyone build network differently and will have a different typology based on their design. They also have a tendency to stick to these designs over all there projects because they are familiar with them. There is no right or wrong, just familiarity. The reason these parameters are available is for flexibility in designing networks and typologies. LON has the similar types of parameters but they are built in the chip from Echlon and the user has no access to them, so as long as you follow the rules the network designers laid out when they set the chip parameters you are all good. If you can not meet their design then too bad rewire the building.

    In a typical network in a Building automation world you should like never need to set most of the a parameters (besides address) unless you are pushing a network to the limits or designing a network "outside the box"

    -Jeremy

  4. #17
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    Quote Originally Posted by kc2dnw View Post
    LON has the similar types of parameters but they are built in the chip from Echlon and the user has no access to them
    By similar types of parameters you must mean the min/max send/receive and send on deltas - for TP/FT-10 nodes, or you might be talking about channel timeouts, packet reorder timer, and channel delay - for IP channels.

    Or perhaps what you're smoking is a little strong, because those parameters are all adjustable.

  5. #18
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    Sticking with a pure bus network (MS/TP or TP/FT-10), which is what the parameters that are being discussed are for, you can adjust the packet latency, burst data frequency, channel capture timer, etc which are all labeled as things like APDU, Max Master, etc in the BACnet world. These do not exist on the LON bus network. Once your cross into IP that is a whole different network typology on both sides of the world. I am talking about network parameters that are not protocol specific but hardware design based. These parameters in any protocol are often relabeled and made available to end users but in the case of LON they are not. This isn't always a bad thing as most people don't understand networking hardware and design enough to know what to do, it just means it's less flexible. Less flexibility translates into easier to use for the end user, until it doesn't work

    -Jeremy


    Quote Originally Posted by digo View Post
    By similar types of parameters you must mean the min/max send/receive and send on deltas - for TP/FT-10 nodes, or you might be talking about channel timeouts, packet reorder timer, and channel delay - for IP channels.

    Or perhaps what you're smoking is a little strong, because those parameters are all adjustable.

  6. #19
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    The Lon parameters you speak of either exist and are hidden from the user or they don't exist. Which is it?

    Lontalk is not a token passing protocol, so it's pretty obvious why a "Max Master" setting doesn't exist there.

  7. #20
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    They exist within the the Echelon chip which is only modifiable by they copyright owner. All networks have these parameters, they are a function of the hardware. It is the protocols choice whether to make them modifiable or available. JCI N2 is the worse for setting parameters very low then making none of them adjustable by anybody, making network management & modification a nightmare but make it very stable.

    There is no right or wrong, only different when it come to networks and protocols. Between the different applications and people different experiences you get opinions about network, but that is all they are. LON is no better then BACnet and no better then any proprietary protocol when it is looked at from a networking perspective, with a properly designed network for the protocol. When discussing application of a protocol then a whole new field of discussion opens up but it is all subjective.

    -Jeremy

    Quote Originally Posted by digo View Post
    The Lon parameters you speak of either exist and are hidden from the user or they don't exist. Which is it?

    Lontalk is not a token passing protocol, so it's pretty obvious why a "Max Master" setting doesn't exist there.

  8. #21
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    Quote Originally Posted by kc2dnw View Post
    The issues addressed here with MS/TP here are issues of lack of understanding of basic networking in the field. ....
    Yr right most setting should never need changing... in fact most of the MSTP setting are pretty much a waste of time....prolly be better indeed if they were hidden.
    Anyway, almost 99% the physical media is the problem

    mstp claims to be easy ... nothing could be further from the truth. Full of holes and pitfalls.
    The addressing schema needs to be 'idiot-proof' ... building a node address schema that falls down when there is a simple clash ...is still plain ol' silly....its just soooo 'last millenium'

    I just downloaded 14 KMC vavs on the bench and increased their MM setting to 30 ... so they can ship to site and (hopefully) be installed without bringing the network to its knees.

    Did connect to the site via VPN and try setting MM on the other existing controllers via the Bacnet object in the JACE but naahh... they controllers wont accept it. so sigh!! ... still gotta physically go to site and change the other 12 existing devices to so that their MM setting is 30 too

    ... or the system wont work....lets also hope I got the MAC addresses all 100% right too heh?

    thanks ashrae.

    happy to hear of another way I can handle this....must be doing it wrong!

    btw ... if this was lon they would have been installed and commissioned via the VPN already!
    1 + 1 = 3 ( *** for very large values of 1)

    ...everybody wants a box of chocolates and long stemmed rose

  9. #22
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    Quote Originally Posted by kc2dnw View Post
    ...making network management & modification a nightmare but make it very stable...
    Stability ... LOL... is the key work here!

    and if MSTP was just a little more stable then we wouldnt be having this discussion at all would we?

    Look LON has its own share of networking issues and gotchas too ... at least it doesnt fall over simply trying to address controllers !
    1 + 1 = 3 ( *** for very large values of 1)

    ...everybody wants a box of chocolates and long stemmed rose

  10. #23
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    Quote Originally Posted by MatrixTransform View Post
    Stability ... LOL... is the key work here!

    and if MSTP was just a little more stable then we wouldnt be having this discussion at all would we?

    Look LON has its own share of networking issues and gotchas too ... at least it doesnt fall over simply trying to address controllers !
    Based on what I've seen using Lon FTT-10, Arcnet/bacnet, and MS/TP bacnet. MS/TP gives the most options for iffy communication wiring. For example; I don't know how many times I needed to install a system using the existing 18/2 twisted shielded wire. It'll work with MS/TP. Try that on Arcnet or Lon.

  11. #24
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    Good day All,

    I do not know if I am the only one, but is anyone else getting tired of the same-old BACNet bashing? Does BACNet have issues, yes. Is there room for improvement, yes... but so is the case with other topologies/technologies as well.

    For those that do not like BACNet, then may I suggest that you simply stop doing any work that requires BACNet? ... tell your customers that you only do <insert preferred technology>... it is pretty simply really. Otherwise deal with what BACNet requires and move on. This endless bashing is pointless and buries some good info/gotchas that others may benefit from.

    Lastly, if you still feel strongly against BACNet's "issues" then why not contact ASHRAE and/or join one of their working groups to see if you can assist with addressing these issues? Again stop complaining and do something about it.

    Cheers,

    Sam

  12. #25
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    people are free to print what they want (within limits)... you may be tired of the debate but clearly it continues heh?
    Id suggest that if you dont like it ...then dont read it.

    we are indeed still waiting for succinct descriptions of the parameters in question arent we?
    So maybe unless you have nothing to actually add, then your point is moot.
    1 + 1 = 3 ( *** for very large values of 1)

    ...everybody wants a box of chocolates and long stemmed rose

  13. #26
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    Quote Originally Posted by MatrixTransform View Post
    people are free to print what they want (within limits)... you may be tired of the debate but clearly it continues heh?
    Id suggest that if you dont like it ...then dont read it.
    <snip>
    That is true... except your Bacnet bashing tends to muddy the waters for potentially worthwhile information that may be beneficial to all.

    Quote Originally Posted by MatrixTransform View Post
    <snip>
    we are indeed still waiting for succinct descriptions of the parameters in question arent we?
    So maybe unless you have nothing to actually add, then your point is moot.
    Perhaps if you would leave your bashing and snide comments out of your questions maybe someone would take the time to answer. That being said at times you raise some valid concerns and insight, but to me they get overshadowed by your "spirited" commentary.

    However, you are right... If I do not like what I see I do have to look... and I have a number of colleagues that choose the latter because of the bickering, bashing, etc that seems to be prevalent.

    Just saying...

    Cheers

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