Combining printhead wires !

[Simon 4]

I want to save some wires to the printhead, and to save some time for try and error I asking into the forum.

My specs are

Extruder with 5V 3 wire fan
BL touch
5015 12V part cooling fan with 4 wires
and x and y endstop switches

I already know that I can save one gnd at the bl touch and one for the endstops.
also I am using the 5 V+ from the BL-touch and the 5v extruder fan
GND bl touch + GND 4 pin fan + GND Endstops are one wire

what else can I combine? Is it possible to connect the heater to GND
I think the 5V fan GND could not be connected to the other ones ?

[deckingman]

@Simon-4 If you can live without the tacho signal you could simply run two wires for each fan which will save 3 conductors. If you change the 5V fan to a 12 V fan (or vice versa) you could use a common V+ which would save another conductor. If you can find the money and somewhere to mount it, you could use a tool board which only requires power and data so 4 conductors in total.

[Simon 4]

@deckingman

CAN-board and changing the setup is not possible.

[deckingman]

@Simon-4 Now that you've edited you first post, I'm not sure how Duet controls 4 wire fans but I suspect it's the same as heaters and the like whereby the Mosfets switch the gnd rather than the positive. In which case, combining the fan or heater gnd with other gnds isn't going to work.

[jay_s_uk]

@deckingman 4 wire fans have an always on power connection and rely on a PWM signal on a separate cable for the control