Duet3 toolboard etc.



  • Hi

    I have a Duet3 board 6HC in use and I am thinking of implementing the Duet3 toolboard...
    But I have come along some thoughts about the selected connectors for the CAN.

    1. On the Main board there is a RJ11 for CAN-FD, ok but why not RJ45 ethernet? RJ45 this is widely used...and probably easier to get then old telefone RJ11. And you have better cable categories! Twisted pair!...

    2. On the Toolboard a JST connector to connect CAN-FD??? Then you need to cut a Phone Cable/Ethernet Cable to crimp to an JST. Kind of strange.

    I would love to use standard cables if possible. Why not using connectors that enable us to buy standard cables?
    Btw. for CAN cables twisted pair is extremely recommended, but I find it hard to find RJ11 twisted pair cables..any sources known?

    On the other hand, if you use the "tool distribution board" you need to connect the CAN FD via these tiny JST to the Toolboard, okay same connector on both sides, but the "tool distribution board" for a single extruder printer is kind of an overkill.
    And how do you deal with the CAN network if from the "tool distribution board" the toolboards are connected like star and not daisy chained? Do you select the longest cable connection and then terminate that one?

    What was the thought behind the selection of the connectors for CAN?

    Please get me right, I love this equipment and its performance, great job of all involved people.
    Just thinking of how to make life easier 😉

    Cheers and stay safe
    Ric



  • RJ11 vs RJ45 - if it can be plugged in wrong it will; to a lesser extent maybe also cost/board space.

    Tiny JST - primarily space concern; they do sell pig tails and the break out board to alleviate this; and a single tool board for a single extruder is also overkill when the main board has 6 stepper drivers.

    The tool distribution board is actually daisy chained if you look at the schematic.



  • @Hornetrider r said in Duet3 toolboard etc.:

    The tool distribution board is actually daisy chained if you look at the schematic.

    Therefore, you put the one and only termination jumper on the distribution board IF it is the last physical board on the RJ11 chain. And bypass any unused tool board connectors (a pair of jumpers each).

    Then you need to cut a Phone Cable to crimp to an JST.

    Yes. And I'm very happy that there is no bulky RJxx on the tool board.

    However, I am unclear what you do about termination in this case.

    CAN cables twisted pair is extremely recommended,

    And almost completely irrelevant for a CAN cable less than one meter long.



  • @Danal said in Duet3 toolboard etc.:

    @bearer said in Duet3 toolboard etc.:

    CAN cables twisted pair is extremely recommended,

    And almost completely irrelevant for a CAN cable less than one meter long.

    Can confirm that this is the case for long cables too - I'm running an old crappy telephone cable that's definitely not in twisted pairs (beacuse that's what was quickly available at the time) thats ~3 m long to an expansion board and it's fine 🙂


  • administrators

    RJ11 cables are commonly used to connect VDSL and ADSL modems to telephone sockets. The better quality ones are twisted pair.

    A convenient UK-based supplier for us is https://www.kenable.co.uk/en/search?controller=search&search_query=high+speed+adsl+cable. To find other suppliers, search for "RJ11 twisted pair" or "RJ12 twisted pair". I did a quick Google search with region set to USA and found
    https://www.cablesondemand.com/Library/InfoManage/Items.asp?category=MPSCat5E&product=MP-52RJ11SNNE
    and https://www.winford.com/products/cbm6.php.

    The connectors can be 6p2c, 6p4c or 6p6c. The minimum is one twisted pair using the two centre conductors, but most cables have at least on more twisted pair using the next two conductors out. Wiring must be straight through. Round cables are usually twisted pair, flat cables usually are not.

    Currently we don't use the flexible data rate feature of CAN, so you can get away without twisted pair. We will probably start using that feature at some point, to support systems with more motors without losing throughput. It will be configurable.



  • thanks for the feedback.

    Twisted pairs will become more crucial the higher the speed and load on the CAN is. A high and fixed transmission rate according to the amount of nodes that are applicable is probably the easiest way to reduce application issues.

    Well okay if you can use the RJ11 cables that come with the VDSL/ADSL modems, that have to be replaced every now and then, then you have it at home anyway, Problem solved 🙂

    But any IT store around the corner has at least RJ45 Ethernet cables...these seem to come more durable for moving cables...personal opinion...
    In the end it doesn't matter that much, but having to crimp a different connector to the cable and than a tiny JST ...well I don't know, it does just not feel good to me.

    @dc42
    what is the current transmission rate setup for the CAN FD?


  • administrators

    The default CAN transmission rate for Duet 3 is 1Mbit/sec. We plan to use 4Mbit/sec for the higher data rate when we turn on bit rate switching.


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