Connecting Servo 1171MG TRAD-RACK

nico.rast

Hi guys! I'm setting up my printer again
I'm converting it into a Voron 2.4 'giant' with the current print bed but in coreXY following the Voron project. I intended to add the TradRack to have the multi-color option. I need to purchase a 3hc board to connect additional motors for the Z axes. But I wanted to understand, in the TradRack configuration, you mount a servo motor 1171MG. Where do I connect it? How do I program it?

Thanks a lot in advance!

achrn

I am not familiar with TradRack, but to connect a conventional servo you use M950 to define an IO as a servo, then use M280 as and when required to set the servo to a particular position. Alternatively, you can use an Out pin, but will need a pullup on it.

I have a servo on IO7 on my MB6HC that opens and closes blades on a vent on the printer enclosure, so my config.sys has

; servo 1 on io7.out (note, needs to be 4, 5 or 7 as these are only PWM capable IO)
M950 S1 C"io7.out"                            ; create servo 1
M280 P1 S10                                   ; set to 10 degree position, which is blades closed

and then when I want the vent open it is M280 P1 S170 and when I want it closed it's M280 P1 S10

Various things to note:

Not all IO headers can do PWM, but https://docs.duet3d.com/Duet3D_hardware/Duet_3_family/Duet_3_Expansion_3HC#inputoutput suggests that IO1 and IO4 on a 3HC can do it.

Servos are aggressive with the power supply. Consider putting it on its own supply. At least, put in a capacitor nearby. See https://docs.duet3d.com/en/User_manual/Connecting_hardware/Motors_servos#connecting-servo-motors. I have used the capacitor option, but mine is a lighter weaker servo than you are proposing, and my servo is moving a very low inertia mechanism.

Servos theoretically want 5V or more PWM signal. Some boards have a connector for a suitable control signal at 5V, but the particular servo I have used is happy at the standard 3.3V signalling on a IO pin with no treatment.

Use an 'ordinary' 'analogue' servo - what radio control calls 'analogue' servo uses the PWM signal that Duet boards generate (though they do it digitally). 'Digital' servos use a serial data stream on the wires and probably fall back to the old style control when they don't get that, but add an extra layer of possible confounding.

nico.rast

1171MG is a DIGITAL servo, I don't have much experience with servo motors, I will have to do some tests.
I hope to find some info on TradRack, there's a genius who should have done it on RRF.

Thank you very much!

achrn

@nico-rast said in Connecting Servo 1171MG TRAD-RACK:

1171MG is a DIGITAL servo,

Well, that depends

JX Servo produce an analogue 1171MG (http://www.jx-servo.com/en/Product/MS/MAS/562.html) and a digital one (http://www.jx-servo.com/en/Product/MS/MDS/570.html). As noted, I suggest you use an analogue one.

Exerqtor

I plan on building a TradRack down the road with a "Fysetc stride max dual" as controllerboard, I however lost some of the steam when Annex announced they were moving away from open source tbh.

It's quite a few macros that need to be made to make it work like intended, in regard to servo control that's the easy part as long as you have a PWM capable output avalible for it.

nico.rast

@Exerqtor Do you find it more difficult to communicate with a different board than the Duet? Or does it remain simple with the CAN bus and just a matter of assigning some addresses?
I didn't know that Annex was stepping out of the open-source project. If I see that it doesn't work well, I'll get the ERCF. Even though I've already built the trad-rack. My real issue is that there aren't many configurations for RRF, and I'm not very skilled in 'free' programming. I like to experiment, but I don't have any studies that could help me.