Duet 2 Ethernet questions

  • Couple Ethernet connection questions here.

    I’m putting my R2x in a garage that has poor WiFi and no Ethernet hookups, so I’m attempting to hook up a Duet 2 Ethernet via powerline Ethernet. (Comtrend PG-9172 if it matters.) But the powerline adapter isn’t talking to the Duet for some reason.

    • When connecting the Duet directly to the powerline Ethernet adapter, no lights come on at the Duet Ethernet port, the powerline adapter says it is on powerline but no LAN connection, and the router doesn’t show the Duet connected.
    • Powerline adapter works 100% correctly with laptop (same outlet, same cable, etc)
    • Duet works correctly on regular Ethernet switch inside the house (DHCP, haven’t tried static IP)
    • Duet Ethernet lights come on when connected directly to laptop
    • Tried putting the printer PSU on the same outlet as the powerline adapter, and running the printer PSU off a UPS to eliminate ground loop issues, no dice either way — no lights. It’s like the powerline adapter and Duet Ethernet adapter just don’t see each other.

    I don’t have the Duet Ethernet adapter chassis ground prong hooked up, and the PSU V- is floating. I don’t THINK that should matter, since it worked fine off a switch/router inside the house.

    Any suggestions for how to troubleshoot this more? I am thinking of putting a switch/hub between them, and trying a static IP address for the Duet. Out of ideas otherwise.

    Second question, vaguely related. Can I put the Duet Ethernet on a PoE switch just for Ethernet without any adverse effects? I assume the PoE switch will not provide power unless the Duet asks for it, and just wanted to confirm.

  • administrators

    1. You may need to use a crossover Ethernet cable, depending on the powerline adapter. Laptops and routers generally auto-switch the connections as necessary, but the Duet doesn't, and perhaps your powerline adapter doesn't either.

    2. I'm sorry, I know very little about PoE. There are multiple implementations of it, see https://en.wikipedia.org/wiki/Power_over_Ethernet.

  • Man, I haven’t had to use a crossover cable in like... 15 years? Good thought, I can make one to test that.

  • Incidentally, powerline ethernet will be a REALLY good solution for the Duet Ethernet if I can get it working. I am thinking about building powerline adapters directly into the electronics enclosures of my future printers (between the power entry and PSU) so they only need a single mains power cord to get power and wired data. That will be a nice, clean solution for wifi deadzones, metal enclosures, etc.

    (Now if only mDNS worked with the Duet Ethernet...)

  • @rcarlyle Now that sounds like a really good idea!

  • administrators

    You may get an impedance mismatch (and hence loss of bandwidth) between the mains wiring and the lead to the printer, because the conductor diameter and spacing won't be the same.

  • @dc42 surge protectors and UPSs are definitely a problem; I do put some of my printers on a UPS so I won't put the powerline adapter inside the enclosure for those. I don't know whether an IEC power cord and a foot of chassis wiring will be an issue. It does work (with some acceptable speed loss) between different breakers in a house, meaning in the US it could be going from a 14ga 15A 120v circuit, across a bunch of outlets, back to the load center, through a GFCI breaker, hop the bus bar to the other 120v leg in the 240v supply, through an AFCI breaker, then go down 12ga 20A 120v wiring through another bunch of outlets. There will be a ton of pigtails and wiring nuts and such in that sequence.

    (For UK/EU people who may not know, US domestic wiring splits 240v hot-hot service from the power company into two separate 120v hot-neutral services where neutral is tied to ground at the load center.)

    Come to think about it, I have no idea HOW it works on separate 120v legs, since all they share is a grounded neutral at one point, but it does work...

    What I'm finding is that powerline ethernet has improved a ton over the last few years. I had a lot of problems back, oh, 2013 or so when I first tried it, but it has been great for me recently.

    The age of your house can also make a big difference. I'm in recent construction now, and powerline has worked great. A previous place I lived in New Orleans (built 1851) probably wouldn't handle powerline well; it had a mix of knob-and-tube wiring from around 1920, ungrounded BX from the 1960s, and NM Romex from the 1990s. There were only three or four grounded electrical outlets in the entire house. Frickin' nightmare for electrical equipment.

  • Ok, I have confirmed that neither a normal ethernet nor crossover ethernet cable allow the Duet Ethernet to talk to the Comtrend PG-9172. Unclear why. I suppose I'll put a switch between them.

    On the Power Over Ethernet note, I can confirm that the Duet works fine hooked up to a POE switch.

  • administrators

    @rcarlyle is it trying to force some other mode such as 10base T or half duplex?

  • @t3p3tony no idea. The powerline adapter doesn’t have all that much documentation. It’s not the sort of thing I care enough about to keep troubleshooting. If it doesn’t work through a switch (powerline-switch-Duet) then I’ll look at it some more. New switch delivering later today.

  • Works fine via switch.


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