This document is relevant to: Duet 2 WiFi / Ethernet
Firmware versions: RepRapFirmware 1.21 onwards, 2.x, 3.x
The pinout is shown below. All 5 driver channels provide 3.6V differential signals on ENA-,ENA+, DIR_,DIR+, STEP- and STEP+.
A 50 way IDC cable is required to connect the expansion breakout board to a second generation Duet board (Wifi or Ethernet). Note that it is not compatible with first generation Duet boards (0.6, 0.8.5), nor with Duet 3 boards
Two wires are required for each balanced signal, it is designed to connect to external drivers that take a balanced input, for example the Leadshine DM556 drivers.
RepRapFirmware 1.21 onwards, 2.x, 3.x
External drivers are configured using M569 and mapped to axes using M584. The Duet 2 WiFi/Ethernet has five onboard drivers (numbered 0 to 4), and the Duet Expansion Breakout Board allows for the connection of up to five external drivers, numbered 5 to 9. Using M569, define the driver number and stepper driver parameters, then map these drives to the relevant axes, eg:
; Drives M569 P5 R1 T2.5:2.5:5:5 S1 ; physical drive 5 goes forwards (X) M569 P6 R1 T2.5:2.5:5:5 S1 ; physical drive 6 goes forwards (Y1) M569 P7 R1 T2.5:2.5:5:5 S1 ; physical drive 7 goes forwards (Y2) M569 P8 R1 T2.5:2.5:5:5 S1 ; physical drive 8 goes forwards (Z) M584 X5 Y6:7 Z8 ; set drive mapping
For more information on how to map axis to these drivers (for example if you want to use external drivers for the X,Y and Z axis) see using external drivers
The Duet Expansion Breakout Board uses a differential output signal of -3.6V to +3.6V. The differential outputs help the LEDs in the optocouplers in most drivers turn off faster. Also they are compatible with drivers that accept RS485 signal levels instead of 5V. Most external drivers are quite happy with the 3.6V differential signals. However, for those few drivers that really do need 5V, you can achieve this by connecting STEP+ from your driver to +5V, which is available on the H6_PWM and/or H7_PWM pin headers (see wiring diagram above), and STEP- for your driver to STEP- on the expansion board. Similarly for DIR and ENA.
Depending on the driver, your ENA input may be a Disable input, not an Enable input. You can fix this by swapping the ENA+ and ENA- wires.
Using the servo headers
Two headers for connecting small hobby servos are available on the Duet Expansion Breakout Board, using Heater 6 and Heater 7 PWM pins. Use them to connect a servo (see Using servos and controlling unused IO pins) or as the control for a probe like the BLTouch.
Note that the output of the PWM pin is inverted, as it is on the Duex2 and Duex5 expansion board, so any connected servo should have the pin definition inverted. For example, in RRF 3, use:
M950 S0 C"!exp.heater7"
The '!' character in the definition inverts the signal.
References and useful discussion links
The board has 4 M4 clearance holes for mounting: