I am asking how the DUET 2 controller is driven.
MRJEON last edited by
I plan to use DUET 2 controller and external servo motor driver. Is it a method of sending pulses directly from the DUET2 controller? Or is it just a signal and the driver handles it?
@MRJEON Is this related to your other thread? https://forum.duet3d.com/topic/18671/i-have-a-question-when-wiring-the-servo-i-o-link
As explained there, Duet sends step/direction pulses. Direct from the expansion header, these are 0 to 3V at 2mA, which is usually not the correct voltage output for many external drivers. So you need a level shifter to get to the correct signal voltage. The Duet 2 Expansion Breakout Board does this, and can be configured for an output signal of -3.6V to +3.6V, or 5V.
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.
So it really depends on the signalling level your external driver expects, and that it can be set in step/direction mode rather than pulse forward/backward, which according to your other thread, your external driver can do.
Edit: For setting up the external driver, see: https://duet3d.dozuki.com/Wiki/Using_external_stepper_motor_drivers#Section_Connecting_external_stepper_drivers_with_differential_inputs
Use the T parameter of M569 in the form Taa:bb:cc:dd to set the timing for the driver: https://duet3d.dozuki.com/Wiki/Gcode?revisionid=HEAD#Section_M569_Set_motor_driver_direction_enable_polarity_and_step_pulse_timing