Dual Heater for a single extruder

jago

Re: Backup thermistor and Dual Heater Cartridges

Hello - actually there are more and more heater blocks available with support for dual heater cartridges and dual pt100 (or other thermistor) slots.

One example is the mosquitto plus, designed for two 50W heater elements and two pt1000.

I was wondering, that the firmware of the duet3d has no valid workaround for powering these cartridges from the two heater ports of the Duet2Ethernet. The PWM for booth MOSFets could be driven from the output of a single PID controller. The temperature from one PT1000 for controlling could be enough and the second could PT1000 could be used for safety e.g. the inputs are not allowed to differ more than X degree...

I am not a specialist in commissioning the duet3d hardware, but after a short research of the possibilities offered by the manual and the wiki I think there is no solution for running two MOSFet channels in parallel.

Physically I can connect booth cartridges in parallel, giving me a resistance of 6 Ohm - so 4Amps @24VDC should be OK for that type of transistor - but perhaps there is another solution or a road-map for a future release maybe implementing this feature..?!

Kind regards

jay_s_uk

@jago you can map 2 outputs to one heater
e.g.

M950 H1 C"3.out0+out2" Q100 T1 ; create heater 1 using ports OUT0 and OUT1 on CAN board 3 (RRF 3.4 or later)

you can also map 2 heaters to 1 tool
e.g.

M563 P0 D0 H1:3 ; create a tool using extruder drives 0 and heaters 1 and 3

you can't join temp sensors together but you could use daemon.g to monitor the second one

T3P3Tony

@jago

If you map both heaters to a single tool then they will be controlled by their associated temperature sensor.

If you map two outputs to 1 heater then the single sensor will control both and the second sensor can be used as @jay_s_uk suggests

@jay_s_uk said in Dual Heater for a single extruder:

use daemon.g to monitor the second one

or use M143 to setup the second sensor to monitor the temperature and generate a fault if its exceeded.

jago

thank you

"..If you map two outputs to 1 heater then the single sensor will control both and the second sensor can be used as @jay_s_uk suggests..."

that sounds like a good starting point for me. Is it as simple as writing:

M308 S1 P"e0temp" Y"pt1000"
M950 H1 C"e0heat+e1heat" T1

to power booth cartridges synchronous from the sensor1 (T1) controller?

jay_s_uk

@jago yep