Big pellet extruder; How to configure the servo motor?

[sbNielsen]

I have just updated the 1XD to be sure firmware is the latest.

The servo driver is running/enabled, cooling is on and i was able to jog it.

When I try to cold extrude, I see a small green LED flash on both the 6HC and the 1XD.

What is most likely, that it is an issue with the servo drive settings, or with my configuration?

I have the servo drive in position mode - pulse control (chapter 6.1.1)

[Phaedrux]

@sbNielsen said in Big pellet extruder; How to configure the servo motor?:

i was able to jog it.

So it's moving?

What is the issue?

[sbNielsen]

@Phaedrux
The jogging was done 'manually' by operating the buttons directly on the driver.

I can't get it to move by using the Duet interface.

I've tried adjusting all of the config.g settings, but no luck.

The only wires that goes to the driver from the 1XD is the step+/- and dir+/-
I've checked for continuity, and the solder is good.

I'm wondering if there is a setting on the driver im missing somewhere.

[droftarts]

@sbNielsen I took a look at the manual for the driver, but it's level of complexity is somewhat greater than other drivers I have looked at. I think it can take a step and direction signal, but I couldn't find anywhere in the manual that said specifically how to set it, and what timing to use in the T parameter in M569:

Taa:bb:cc:dd (firmware 1.21 and later) Minimum driver step pulse width, step pulse interval, direction setup time and direction hold time, in microseconds (only applies to Duet 2, Duet 3 Mainboards and the Duet 3 Expansion 1XD)

I see you have set it to:

M569 P122.0 S1 R1 T5:5:5:5

But it may just be too fast. To be fair it isn't very fast, and I'd expect some movement, which makes it feel a bit more like a driver configuration error.

Ian

[sbNielsen]

@droftarts
Thanks for having a look Ian!

Yes, I have been down the same path but the driver can take up to 1mHz so that should not be a problem.

As far as i can tell, the 'Position mode' should be the step/dir mode, and I have enabled the driver/motor as default on start up.

I will have another crack today and see if i missed something.

[droftarts]

@sbNielsen have another look at how it is enabled. It may be that it doesn’t need an enable signal to be moved manually by the driver. Most stepper drivers are ‘active disable’ ie expect 0V to enable, 5V to disable.

Ian

[sbNielsen]

@droftarts
I just tried to put a multimeter between the step+ and step-, and I measured a constant 5V.

5V when not cold extruding, and 5V when pressing extrude.

Then I tried to measure the Hz frequency between the step+ and step-, and I could not register any - also not when pressing extrude.

I don't know if any of that ^ is as expected?

I thought I should be able to see the Hz on the meter when hitting extrude?

[droftarts]

@sbNielsen said in Big pellet extruder; How to configure the servo motor?:

@droftarts
I just tried to put a multimeter between the step+ and step-, and I measured a constant 5V.
5V when not cold extruding, and 5V when pressing extrude.

That is expected, I think. See https://docs.duet3d.com/Duet3D_hardware/Duet_3_family/Duet_3_Mainboard_6XD_Hardware_Overview#connecting-external-motor-drivers

The Step and Dir outputs from the 6XD are either low (when "on") or floating/high-impedance when "off".
The Enable output is either low when "on" and high impedance when "off", or vice versa, depending on the position of the 'Driver Enable Polarity' (En_Pol) jumper.

So it may be that the driver just need to be configured for this signal. Same for enable, depending on how you have set the jumper.

Then I tried to measure the Hz frequency between the step+ and step-, and I could not register any - also not when pressing extrude.
I thought I should be able to see the Hz on the meter when hitting extrude?

That may be down to your multimeter, which may be expecting a sine wave rather than a PWM signal. Usually an oscilloscope is used to see the signal.

Ian

[sbNielsen]

@droftarts
Ok, so far so good then.

I have sent an email to Lichuan tech support now, hopefully they can find the issue.

[sbNielsen]

@droftarts
I spoke with the store who sold me the motor/driver, and they test each one before selling and usually the issue is on the control/Arduino/Duet side.

I get a reading when sending M115 B122, so there is a connection to the 1XD.

All my config.g numbers are within a reasonable/expected value, so that an extrude command from the Duet WC should cause some kind of motion.

Could this be a fault on the 1XD board, failing to send the frequency? Does that ever happen?

[sbNielsen]

@sbNielsen
Another sign that there is activity on the CAN bus, is that when i press extrude I get a brief flash of green on the 1XD.

So a signal is definitely sent from the 6HC and received by the 1XD

[droftarts]

@sbNielsen Have you tested both 1XD boards? I can imagine a fault on one board, but not on both. If you don't have an oscilloscope, you could wire an LED on each output (as the signalling is 5V), and see if they light up during the move (you may have to adjust the frequency to do this).

Ian

[dc42]

@sbNielsen did you wire the servo inputs like this from page 11 of the manual, with 1XD STEP+ and STEP- acting as PUL+ and PUL- respectively? If not, how did you connect them?

Have you set valid parameters in this table from section 6.1.2 on page 19?

[sbNielsen]

@dc42

• did you wire the servo inputs like this from page 11 of the manual, with 1XD STEP+ and STEP- acting as PUL+ and PUL- respectively? If not, how did you connect them?

Yes, thats how I wired it.

• Have you set valid parameters in this table from section 6.1.2 on page 19?

Yes. I had it in Position mode (external pulse control) P02-00:1 and P05-00:0. I also tried to change various other params to see if they were blocking - no luck.

I spoke with the store I bought the motor from. They have not heard about this before, and puts the fault likelihood on the Duet.

I just tested another external driver + stepper motor on the same 1XD board - this also failed.

So it starts to look like an error with the 1XD.

I have just ordered another one, and will test the new one as soon as it arrives.

[droftarts]

@sbNielsen I know you updated the firmware on your 1XD, but looking back through the thread I can't see what version your 6HC is on. Can you send M122 and M122 B122 and post the results, just in case?

Ian

[sbNielsen]

@droftarts

Yeah sure. They're both are up to date.

[droftarts]

@sbNielsen Actually, they are not. Your main board 6HC is on a older beta release of 3.5, and your 1XD is on 3.4.6. Please either downgrade your 6HC to 3.4.6, or update both boards with the 6HC and 1XD firmware here, which is 3.5.0-rc.1++: https://www.dropbox.com/scl/fo/gaxzegafmnmagaefo9mgc/h?rlkey=hk4wpttdje76oews8zkuh86q3&dl=0

Ian

[sbNielsen]

@droftarts

My god... I updated both boards and now at least the external stepper driver/motor is responding!

Can't believe it, I had updated the 1XD to - what I tought was - the latest version exactly to avoid this.

Will try and plug in the servo and hopefully that will work too!

Haha great friday gift so far!

[sbNielsen]

@droftarts
I just plugged the servo, and it works!

Thank you for the support!