Network terminator

BrianZ
BrianZ Registered Users Posts: 1
Can someone please explain to me what these are needed for?  I see that the control panel and inverter both have two RJ45 ports, so with what I'm understanding, these devices connect via Ethernet.  What is the point in the terminator plug then?  Just to close off unused ports?

Comments

  • Wheelman55
    Wheelman55 Registered Users Posts: 233 ✭✭✭
    I’m certainly not an expert…others will chime in who know more. 

    My Schneider gear and Discover battery all talk to each other via a XANBUS network. Each piece of gear is daisy chained to the next with a network terminator at each end of the daisy chained gear. 

    Off-Grid in Terlingua, TX
    5,000 watt array - 14 CS 370 watt modules. HZLA horizontal tracker. Schneider: XW6048NA+, Mini PDP, MPPT 80-600, SCP. 390ah LiFeP04 battery bank - 3 Discover AES 42-48-6650 48 volt 130ah LiFePO4 batteries
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    The xanbus uses the same connector scheme as ethernet, but has DC voltage on several pins and will fry ethernet gear you attach.

    It uses the same ethernet cables, but xanbus must be terminated with a proper load at each end of the data network, or data flow becomes unstable.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    A terminator's basic function is to stop "echos" in the signal cable.

    https://www.kele.com/content/blog/2014/01/17/the-rs-485-network-terminator

    More or less--You clap your hands and you hear the echo from across the valley. Or you are in a long hall way and hear an echo from the open doors at the end of the hall. That is because of "impedance" mismatch.

    The sound travels outwards from you in the free air--And then hits a mountain (solid wall) and reflects back. Or free travel of sound down the hall and hits the open end--Another change of "impedance" of the air column.

    Same thing with electrical cable... You send a pulse down the cable and it hits an open wire (infinite resistance) and you get an echo back--Which confuses the other receivers on the signal wire.... Same thing if the signal hits a dead short, then a pulse (opposite polarity of "open wire") is reflected back... A terminator if the "characteristic impedance", matches that of the signal wire and since no impedance mismatch, the signal is not reflected.

    The details do matter--One way transmission on the wire (only need terminator on receiving end of the wire). Or bi-directional line (device sometimes transmits and sometimes receive on the same wire)--Need termination at both ends.

    And you can supply power (to power small devices on the cable, or hold the signal wire with a "soft" 0 or 1  level to prevent "noise" being received and confusing the systems).

    And as Mike says... The same "cable plug" does not mean that electrically, the transmitters and the receivers are the same.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Riley
    Riley Registered Users Posts: 67 ✭✭
    The xanbus is actually more like mod-bus I think. 
    Not ethernet at all. 
    Off-grid: XW+6048 / 48V FLA battery bank (428 A/H (Rolls S-550 batteries)) / Conext MPPT 60 150 charge controller / SCP / Insight gateway / 12 - 260W solar panels / Kohler 12KW 12-RES propane genset