CAN Bus cable

[J.Helps]

Hi there!
I am building a large 3D printer for my master's thesis and am having difficulty finding an unshielded twisted pair cable with a 120 ohm characteristic impedance for long cables. Is there a problem with using shielded twisted pair cables, which are more readily available? The Duet documentation recommends using unshielded cables for long distances, but I am unsure of the reason.
Additionally, I am using 10 motors with 10 expansion boards (one board per motor) and was wondering if I can connect all of these boards in series using a CAN bus cable with four wires (two for the RJ11 connector and two for power supply). This would simplify my cable management, even if I use a separate cable for power supply and the CAN bus, but still connect them in series.
Best regards,
John Helps

[dc42]

@J-Helps yes you can use shielded twisted pair and shielded RJ11 or RJ12 connectors.

If the 10 boards are EXP1HCLs then I don't advise daisy chaining the power to them all. Instead I suggest you daisy chain at most 3 or 4 and run each chain back to the PSU. If the boards are EXP1XDs then the power requirement is very low and daisy chaining power to them all should be OK.

[J.Helps]

@dc42 Thank you very much!
I have another question: How does the M597 command work to avoid collisions with two independent gantries with the new multiple motion systems feature of reprap firmware? I mean, if I set the "safe" distance of the gantries to 20mm, what happens when they reach that distance? Does one of them stop or slow down?

[dc42]

@J-Helps if a potential collision is detected then the print is aborted.