The Duet range of controller boards have a number of outputs to directly connect heaters. These are supplied by VIN voltage, ie the voltage of the PSU that powers the Duet, and are generally protected by a fuse. Mainboards usually have one 15A output, primarily intended for a 3D printer heated bed, and two or three (depending on board) 6A outputs, primarily intended for a 3D printer's extruder heaters. See the wiring diagram for your board for specific information and wiring. Additional heaters can be controlled by adding expansion boards, and/or by using PWM outputs on board to control Solid State Relays.
Heater outputs can also be used for other applications, eg CNC spindle control, laser cutter/engraver control, pumps and other electric motors that draw more current or require a higher voltage signalling level than other PWM pins on the board can support.
|Board||'Bed heater' output||'Extruder heater' outputs||RRF3 pin name||RRF2 heater number|
|Duet 3 Mainboard 6HC||1 x 18A (15A fuse)||3 x 6A||out0 (bed), out1, out2, out3||-|
|Duet 3 Mini 5+||1 x 15A (15A fuse)||2 x 5A||out0 (bed), out1, out2||-|
|Duet 3 Expansion 3HC||-||3 x 6A||out0, out1, out2||-|
|Duet 3 Toolboard 1LC||-||1 x 5A||out0||-|
|Duet 2 WiFi/Ethernet||1 x 18A (15A fuse)||2 x 6A||bedheat, e0heat, e1heat||0 (bed), 1, 2|
|DueX2 and DueX5||-||2 (DueX2) or 5 (DueX5) x 6A||duex.e2heat to duex.e6heat||3 to 7|
|Duet 2 Maestro||1 x 18A (15A fuse)||2 x 6A||bedheat, e0heat, e1heat||0 (bed), 1, 2|
Note that some boards are rated to 18A on the bed heater channel; however all Duets are supplied with a 15A fuse fitted (18A fuses are difficult to source). If you need 18A on the bed heater channel then you need to fit a 20A fuse and take further precautions against over-current. This rating has been increased from 15A due to updated thermal testing.
RepRapFirmware has some limits on how heaters can be configured. As of RRF 3.4 these are:
|Duet 3 MB6HC/6XD||Duet 3 Mini 5+||Duet 2 WiFi/Ethernet||Duet 2 Maestro||Notes|
|MaxHeaters||32||32||10||4||The maximum number of heaters|
|MaxPortsPerHeater||3||2||2||2||The maximum number of output ports per heater|
|MaxMonitorsPerHeater||3||3||3||3||The maximum number of monitors per heater|
|MaxBedHeaters||12||2||4||2||The maximum number of bed heaters|
|MaxChamberHeaters||4||2||4||2||The maximum number of chamber heaters|
|MaxHeatersPerTool||8||2||8||2||The maximum number of heaters per tool|
See the following sections for more detail on connecting and configuring heaters:
Connecting and configuring extruder heaters
Connecting and configuring a bed heater
Connecting and configuring a chamber heater
Tuning the heater temperature control
Note that while it's possible to configure a heater with no temperature control, for safety all heaters should have a temperature sensing channel associated with them. The Duet series supports 4 types of temperature sensor: thermistor and PT1000, thermocouple, and PT100. For more details see Choosing temperature sensors.