External Drives Wiring Questions



  • Hello! I am using a Duet Ethernet along with a Duex5 and am looking to connect four external drives. It is my understanding that you cannot use the default x/y/z headers on the Duet Ethernet because these output post-processed signals from the TMC2660 driver chips. Instead, you have to remap the external drivers to headers 5-8. I also wanted to clarify something from the wiki. It says that you cannot use the test points for the x/y/z drives as inputs into an external driver, but if I am only using the points for step direction input into my external driver, would this be okay? I assume not, but I figured I would check!

    Additionally, if I do remap the x/y/z to drives 5-7, is it possible to remap the built-in (but now unused) x/y/z drivers/headers to use as additional extruders? I would also need to remap the heater output for drives 5-7 because the x/y/z drives do not normally have heaters. If this is possible, it would be extremely helpful!

    Thanks in advance for the advice!


  • administrators

    @mazo1 said in External Drives Wiring Questions:

    Hello! I am using a Duet Ethernet along with a Duex5 and am looking to connect four external drives. It is my understanding that you cannot use the default x/y/z headers on the Duet Ethernet because these output post-processed signals from the TMC2660 driver chips. Instead, you have to remap the external drivers to headers 5-8. I also wanted to clarify something from the wiki. It says that you cannot use the test points for the x/y/z drives as inputs into an external driver, but if I am only using the points for step direction input into my external driver, would this be okay? I assume not, but I figured I would check!

    You can't do that, because the pins labelled EN/CS are actually chip select pins for the TMC2660 drivers, not driver enable pins.

    Additionally, if I do remap the x/y/z to drives 5-7, is it possible to remap the built-in (but now unused) x/y/z drivers/headers to use as additional extruders?

    Yes you can. Use the M584 command in config.g to remap axes and extruders to different drivers. It sounds like you need something like M584 X5 Y6 Z7 E0:1:2:3:4.

    I would also need to remap the heater output for drives 5-7 because the x/y/z drives do not normally have heaters. If this is possible, it would be extremely helpful!

    Heater outputs are independent from drives, so you don't need to remap them.



  • @dc42 Thank you for taking the time to explain that to me and answer my questions! If anything else comes up, I will be sure to ask here.


  • administrators

    I just realised: you said you want to use external drivers, but you also said you have a DueX5. That means you will face the same issue on the expansion header: the 5 EN/CS pins on the expansion header are used as CS pins for the TMC2660 drivers on the DueX5.

    If you need to use a DueX board to support additional heaters or fans, and you also want to use 3 external drivers, you should use a DueX2 board instead.

    You can also connect 2 external drivers to the CONN_SD connector.

    Bear in mind that the built-in TMC2660 drivers support higher currents than other 3D printer control boards, so they can drive some types of Nema23 motor directly.


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