M569.7 motor brake on duet2 ethernet

[djstree]

Hi!

Can M569.7 be used on duet2, using the high current bedheat output to activate/deactivate a Z axis brake? Something like... ?

; Drives
M569 P3 S0                     ; extruder e1 goes backwards
M569 P5 S1 R1 T2.5:2.5:5:5     ; Z physical drive 5 goes forwards
M569 P6 S0 R1 T2.5:2.5:5:5     ; Y physical drive 6 goes backwards
M569 P7 S1 R1 T2.5:2.5:5:5     ; X physical drive 7 goes forwards
M584 X7 Y6 Z5 E3

; Z break
M569.7 P0.0 C"bedheat" S50     ; uses bedheat output control the brake with 50ms delay

[dc42]

@djstree you can do that but you must add a flyback diode in parallel with the brake solenoid.

[droftarts]

@djstree I've added the following to the Gcode dictionary M569.7 entry:

As long as the brake solenoid max current draw is <2A and it is rated for the VIN voltage used, it can be directly controlled by OUT pins (Duet 3) or FAN pins (Duet 2) which have flyback diodes, at VIN voltage (not using 5V/12V onboard regulator). If the current required is >2A, a heater output can be used, however you must add a flyback diode in parallel with the brake solenoid.

Ian

[djstree]

@dc42 @droftarts

The Teknic NEMA 34 brake appears to require 0.41 amps so fan2 might be usable.

https://teknic.com/products/spring-applied-power-off-brakes/NEMA-34-brake/

; Z break
M950 F2 C"nil"               ; disable fan 2 and free up the associated pin
M950 P7 C"fan2"              ; create gpio pin 7 for Z brake using diode protected fan2 output
M569.7 P0.5 C"fan2" S20      ; Z drive 5 to use fan 2 output control the brake with 20ms delay

Thanks!