The Duet 3 Expansion 1HCL is a CAN-FD connected expansion board for the Duet 3 Mainboard 6HC, Duet 3 Mainboard 6XD and Duet 3 Mini 5+ that is designed to provide a high current stepper motor driver, combined with multiple interfaces for position feedback. It has a number of peripheral inputs and outputs for functions such as sensing motor temperature, controlling a brake and axis endstop.
Product page is here: https://www.duet3d.com/duet-3-expansion-1hcl
Documentation is here: https://docs.duet3d.com/Duet3D_hardware/Duet_3_family/Duet_3_Expansion_1HCL
As always please discuss this on the Duet3d forum: https://forum.duet3d.com/