@dc42 thank you for fast response. I am looking for 13th and 14th (or even 15th and 16th) stepper driver so not existing expandability options within duet2+duex5. So not exactly what i asked but I'll settle for this kind answer.
Duet 3 mini with expansion would give 7 stepper drivers each, so 14 needed, but i do have to read up if this would also have 8 channels of PWMs for fans, five heaters + at least 1 PWM for bltouch/probe and stuff that is needed to drive one proper IQEX...
I'll have to read up but ain't thrilled on going anything mini. It's just the ordinary "go duet3" way then OR doing an addon PCB for multiplexing.. Ourighty then.
i had the wrong firmware selected. Turns out you need RepRap/Sprinter, not RepRapFirmware, because this particular script does not work with G10 commands and therefore stuff did not work.
Thanks anyway @Stephen6309 and @oliof
@MaracMB I also used to run Duet3 with a Duex 5 and 10 motors. In that case, the boards were in vented enclosures and I had thermostatic fans blowing air over the back of the boards. That arrangement was more than sufficient to keep everything cool.
It got pretty compact.
Needs a lot of work still to get the flat round cabling routed to both sides of X gantries from the bottom, then flat cables from there to each head, make breakout boards on toolheads for ribbon cables etc.
But all in all. There is progress
@dc42 thanks for the input.
The short power cycle is due to me trying to post a “clean” report. It could run for hours just heated, homed and ready to execute. It was at the time just after or in time of first gcode extrude execution, so when priming, it rebooted. Only then and when manual extrusion was sent to it. It could sit for hours otherwise.
I suspected the wires of thermistors as both printheads have exact same components, yet the PID values were different. But not that much to be obvious. That alone gave me clue to rewire because wiring truly looked ok.