PWM MOSFET control
All power element which are controlled are connected to PWM controlled MOSFETs which drain current to the ground ('sinking' connections). These sinking lines are indicated by an arrow. PWM frequency varies depending the application and is user adjustable for controlled fans. MosFET may fail and stay permanently conductive, in this case the connected element will go full power with the only possibility to stop being to shutdown the power supply, which is only possible if the Power Supply could be stopped via the PS-on signal. See Safety page.
End stops connection
Signal shall never exceed 3.3V. Safety shall be provided in case of ground wiring fault. A solution is to add a safety diode. An optocoupler shall be the safest solution.
The signal line is connected to an on board LED (see schematic), so if endstops are electronic circuits, they shall be able to drain sufficient current through the LED to rise signal to high. This shall be taken into account if using a voltage divider (to limit the signal voltage).
All positive fan pins are connected to Vin.
The pinouts are on the back of the board (V 0.8.5), a KiCAD export shows the back below for reference (this is the view from the bottom of the board, so is mirrored):
There is more detail on the pinouts on the Duet pinout page.
BED and chamber heater SSR wiring
5V controlled fan
This schematic is also valid for Duet 0.6.
Beware of the Bed, heater and fan connector polarity, which is different from the 0.8.5 board
5V controlled fan
Multiple steppers wiring
Identical steppers shall turn in same direction. To have them running in opposite direction, swap the wires of one coil. By example, you can swap yellow and green wires on the Z2 stepper connector.
To avoid confusion, it is better to use identically wired cables, with same colors.