Toolchanger printer with DueX5 external stepper drivers

Eumldeuml

Hi all!
I just wanted to confirm something from the documentation. First of all, my (soon-to-be) printer is a CoreXY toolchanger with six independent tools that runs with a Duet 2 Wifi and a DueX5. That means, from the 10 integrated stepper drivers I need 7 drivers for tools and Z axis. The XY system runs on two JMC stepper servos that I need to connect to one of the boards.
From what I read in the documentation, this is either done

through the expansion header (which is occupied in my case)
with the pass-through connector DB S/D/E on the DueX5 (which requires the board to be put into DueX2 mode which limits my available stepper channels?..)
or through the CONN_LCD connector.

I plan to go with the last option as it doesn't seem to have any drawbacks. Is this valid?
Also I want to use the PanelDue 7i which I intend to connect with the four-pin connector. This won't allow me to use the SD card anymore but I'm pushing gcode over WiFi anyway.

I'll be very glad if someone could tell me that my approach is good or that I'm overlooking something.
Thanks and have a great weekend!

dc42

@Eumldeuml yes that's a valid way of connecting it. In fact you can still connect the PanelDue to the Due using the ribbon cable if you like because it plugs into the CONN_SD connector, not CONN-LCD.

The signals on CONN_LCD are low current 3.3V signals, which you will almost certainly need to boost to 5V at greater current to drive your external step servo drivers. One option for this is to use our expansion breakout board.

Alternatively, as you are only using 3 of the 5 drivers supported by the DueX5, you could connect both the DueX5 and the expansion breakout board to the expansion connector, using a ribbon cable with three connectors. Then connect the step servo drivers to the driver 8 and 9 outputs on the expansion breakout board. You won't be able to use the Enable pins of those outputs, but most external drivers don't need an Enable signal anyway.

Eumldeuml

@dc42 Alright, thank you very much for the information!

Eumldeuml

@dc42
Two more questions after buying the Expansion Breakout board:

The differential enable pins switch between on and off with 5 kHz when the printer is idle and also when a move command is given (though the motors won't move as they are in alarm state due to the fast switching). Disconnecting the enable wires does work, although I'd like to be able to switch the motors off via software
Do I need to disable the drivers on the Duex5? When moving X or Y, there is a warning in the console that the phases might be disconnected (which they technically are, as there is nothing connected to the outputs). When I disable the drivers, the servo motors start moving very slowly upon startup of the Duet and on the PanelDue there is a warning about overtemperature of those drivers.

dc42

@Eumldeuml said in Toolchanger printer with DueX5 external stepper drivers:

The differential enable pins switch between on and off with 5 kHz when the printer is idle and also when a move command is given (though the motors won't move as they are in alarm state due to the fast switching). Disconnecting the enable wires does work, although I'd like to be able to switch the motors off via software

I did tell you that you won't be able to use the Enable pins if you use both the EBB and the DueX.

Do I need to disable the drivers on the Duex5? When moving X or Y, there is a warning in the console that the phases might be disconnected (which they technically are, as there is nothing connected to the outputs).

You can do, however just setting them to a current <= 500mA or not setting the current for those drivers at all should suppress that message. If you want to disable monitoring of those drivers, see the R-1 parameter of the M569 command.

Eumldeuml

@dc42 Sorry, apparently I misread your statement somehow. Thanks for clarifying!