Connect servos on a duet WiFi

[andres_13]

Hello everyone

Is it possible to directly connect a servo motor, or a closed-loop stepper motor to a duet wifi card? If not possible then what devices would I need?

Thanks a lot

[Phaedrux]

Do you already have the Duet wifi? Do your motors accept step/dir signals?

If you don't already have a Duet, take a look at the Duet 3 6XD which is designed with servos and external drivers in mind.

https://docs.duet3d.com/en/Duet3D_hardware/Duet_3_family/Duet_3_Mainboard_6XD_Hardware_Overview

[mrehorstdmd]

@andres_13 I use two servomotors in my sand table with a Duet WiFi card and an expansion board to get step/dir/en signals out of the controller.

The sand table uses iHSV servomotors with the differential step/dir/en inputs directly connected to the expansion board.

The two purple PCBs are protection circuits to keep the servomotors from destroying everything wired in parallel with them in the event of a high speed crash. If you have a well stocked junk box it might be cheaper to just use analog power supplies for the motors and an additional power supply for everything else.

[alankilian]

@mrehorstdmd said in Connect servos on a duet WiFi:

The two purple PCBs are protection circuits to keep the servomotors from destroying everything wired in parallel with them in the event of a high speed crash.

Boy, howdy! I've sure been there.

I wrote the firmware for a nationally-known adjustable bed company and we had an adjustable frame with DC motors that ran the head and foot up and down.

There was a requirement to load both head sides with 300 pounds and load each foot end with another 300 pounds, run them all the way up, start running them full-speed down, and emergency stop half way down.

I wrote the code, loaded the bed, ran the test and BANG! We blew about half the parts off the board.

It took the electrical engineers a while to figure out how to keep that back EMF-generated voltage contained to parts that cold handle the stress.

BIG CNC machines have coils that look like they come from a stovetop to get rid of these things and we couldn't do anything like that so I thin the solution was something like 25 Zener diodes all in parallel.

[andres_13]

@Phaedrux Yes, I already have the Duet wifi for a few years on a large format 3D printer with nema 17 and 23 motors, but unfortunately they lose steps due to lack of power, so I'm thinking of using servo motors with the duet wifi. I have not bought any servo yet and by the way I would like you to recommend some servo models that are compatible to do this installation.