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 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 it is not compatible with first generation Duet boards (0.6, 0.8.5).
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.
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 (available on the two Servo connectors), 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.
References and useful discussion links
The board has 4 M4 clearance holes for mounting: