Interconnect of two XW mppt Controllers

silvertop
silvertop Solar Expert Posts: 155 ✭✭✭✭✭
in Advanced Solar Electric Technical Forum #1
I thought I'd read on another thread here, that short cat-5 cables could cause communication problems. Does anyone know if this is true? I have my second XW coming; no SCC they will just be conneced with the ethernet for shared data. They will be 6 Inches apart, and the cable I have on hand is 25 foot 24 GA. Would really like to use a nice short cable. Any ideas?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,641 admin
    #2
    Re: Interconnect of two XW mppt Controllers

    From generic signal quality theory, Cat5 Ethernet is point to point--so there should be no issue with minimum cable length.

    With XanBus--It is not a point to point network, but a daisy chain... Basically, one common electrical data path with multiple receivers/transmitters scattered along the length of the "bus".

    Depending on a lot of issues--If you have more than two units on a daisy chained bus, then there may be some minimum distance that would be good to keep between transceivers... (typically, daisy chain buses will have a terminator at each end of the physical bus--like Xanbus requires).

    In the case of Xanbus--I am not sure that they have a minimum connection length issue between units--but possibly more of a total bandwidth issue--As they add units to the common bus, the devices have more data to send than can be managed by their bus controller/messaging protocol.

    The other thread were I made a suggestion to try longer cables between multiple Xanbus devices did not make the problem go away (as I recall). So, there may be other issues ("chatty devices" using up bandwidth, improper configuration, problems with the bus devices themselves, bad cable, etc.). Chatty devices does appear to be a Xantrex design issue (nothing you can fix).

    In any case, there is no worry about electrical damage--just signal quality. So, if you have a small jumper cable to try--why not.

    That is about all I know about the issue.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • silvertop
    silvertop Solar Expert Posts: 155 ✭✭✭✭✭
    #3
    Re: Interconnect of two XW mppt Controllers

    Thanks for the info. I am looking into purchasing shorter cables and will let you know what happens.
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  • silvertop
    silvertop Solar Expert Posts: 155 ✭✭✭✭✭
    #4
    Re: Interconnect of two XW mppt Controllers

    I just received my two foot cat 5e cable and interconnected my two XW's, all is well with both units communicating. So far I am very pleased, a very nice set up!
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  • tallgirl
    tallgirl Solar Expert Posts: 413 ✭✭
    #5
    Re: Interconnect of two XW mppt Controllers

    Charge controllers aren't the big offenders on a Xanbus -- it's the inverters that create most of the traffic.
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  • deacon
    deacon Solar Expert Posts: 33 ✭
    #6
    Re: Interconnect of two XW mppt Controllers

    I am currently running 1 XW mppt60-150 SCC and 1 xw4024 inverter. I have a short 5' cable from the SCC to the inverter and then a 260' run of cat5E twisted pair from the inverter in the barn to the XW SCP in my house. It is way longer then they recommend but I have had no issues so far.
    I am adding 2 more XW mppt60-150 SCC's next week in the loop so we shall see if that will be the straw that breaks the Xanabus's back.
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  • huntep
    huntep Registered Users Posts: 9 ✭✭
    #7
    Re: Interconnect of two XW mppt Controllers

    I could be wrong but from what I've read so far the Xanbus follows roughly the same distance limitations as LAN based ethernet. ie. 100meters cat5 run. or ~300feet.

    I cannot find however, anyone to state that the xantrex XW Hybrids can be connected to a LAN so that it can be monitored across the net. Observing the Xanbus rules with terminators etc. connecting one network to another and the software to interface the units should be common place...shouldnt it?

    Hope I'm not hijacking your thread..
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  • Dr. Strangelove
    Dr. Strangelove Solar Expert Posts: 49 ✭
    #8
    Re: Interconnect of two XW mppt Controllers

    In the Xantrex Hybrid Inverter Installation Guide, there is the following warning:
    CAUTION: Equipment Damage

    Only connect to other Xantrex Xanbus compatible devices. Although the cabling
    and connectors used in this network system are the same as ethernet
    connectors, this network is not an ethernet system. Equipment damage may
    result from attempting to connect Xantrex Xanbus to different systems.

    I think what you want (or not) is the Xantrex "Gateway" which provides a kinda interface to an ethernet network. There is a thread about it in this forum (spoiler alert): "Xantrex Gateway is extremely dissapointing".
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  • Joe_B
    Joe_B Solar Expert Posts: 318 ✭✭✭✭✭✭
    #9
    Re: Interconnect of two XW mppt Controllers
    Dr. Strangelove wrote: »
    In the Xantrex Hybrid Inverter Installation Guide, there is the following warning:



    I think what you want (or not) is the Xantrex "Gateway" which provides a kinda interface to an ethernet network. There is a thread about it in this forum (spoiler alert): "Xantrex Gateway is extremely dissapointing".

    What the Dr. Said, Xanbus is not Ethernet, it is a version of CANbus and not compatable. The gateway is the hardware bridge between the two but the software for the gateway is a joke so unless you plan on writing your own application, forget about connecting the XW to your computer in any usefull way.
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  • Dr. Strangelove
    Dr. Strangelove Solar Expert Posts: 49 ✭
    #10
    Re: Interconnect of two XW mppt Controllers
    Joe_B wrote: »
    Xanbus is not Ethernet, it is a version of CANbus and not compatable.

    That alone, sir, is worth the price of admission. The gears are turning, and the potential for strange and terrible things is being unleashed (slowly). My latest car is chock full of CANbus, so that was the direction I have been heading in terms of new equipment and experimentation. Looking into my crystal ball, I see a reflashed Xantrex Gateway lying on my lab bench in the distant future.

    Thank you.

    Andrew
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  • Joe_B
    Joe_B Solar Expert Posts: 318 ✭✭✭✭✭✭
    #11
    Re: Interconnect of two XW mppt Controllers

    Well that would be just great, I know for a fact that you can control the system as well as monitor it. (Dont ask me how I know this:D) But there is a protocol specification I can email you if you are serious.
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  • Dr. Strangelove
    Dr. Strangelove Solar Expert Posts: 49 ✭
    #12
    Re: Interconnect of two XW mppt Controllers
    Joe_B wrote: »
    Well that would be just great, I know for a fact that you can control the system as well as monitor it. (Dont ask me how I know this:D) But there is a protocol specification I can email you if you are serious.

    Wow, that would be awesome. I have no doubt that the control aspect is in the bus protocol because the SCP uses it too. I'm not ready for the project right now ("distant future") as the house is being remodeled by narcoleptics. I have just signed on my contractor for ""Phase 2" and the solar garage is down the road in "Phase 4". The lab won't be ready until after "Phase 3". But it would be nice to study in the mean time.

    I have a suspicion that the Xantrex Gateway project was farmed out to an outside company, that was in over their heads, they failed, and Schneider management couldn't justify the ROI to try again. I've seen projects fail like this - none of mine, of course. Here's a thought: imagine a Chumby 8 as the new SCP with "eight-by-ten color glossy graphs with circles and arrows..." Crazy? you bet. But, as Peter Sellers has said: "It could be done with computers."

    Andrew
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