Posts made by john

This seems like a really great idea, especially for people who are tweaking settings a lot to fine tune behavior. I do this manually by saving entire config files with names like "config_original.g" or copying lines of text to track what settings I was using. It can be a pain, and certainly confusing.

Would each file be called "config.g" still? I'm wondering if config.g could be the master config, but config1.g or config2.g could be in the same directory and hold the different settings that you could swap to with M98.

We run leadshine closed loop stepper motors off external drivers connected to the duet through the expansion breakout board.

We keep seeing a little step at the end of every movement that looks like the motor didn't quite get to to where it wanted to go. Generally motors run smoothly from origin to destination, but this is smooth up until about 1.5 mm from the final spot after which the stepper motor "jumps" like its performing a cleanup step to get to where it needs to go.

I am not sure the cause, or how to better describe it. Anyone have experience with this?

Does anyone have a source for custom length, crimped, wires in specific gauge and # wires bundled together? We spend a lot of time cutting, stripping, and crimping wires and want to try to decrease this labor cost. Wondering if there is a service where you pay them to create the wires you need for you. (Small team here, so time is extremely valuable).

Or does everyone just buckle down and churn through it themselves?

@da-sid-mon What do you mean "no makeup for error?" I am not saying they are perfect, but the driver-motor combo that I indicated above does attempt to correct the lost steps. The bigger problem that I don't see either of the solutions (mine or your linked servos) is that debris / mechanical fault causing lost steps won't be remedied by closed loop. The only thing that these solutions do in my mind is indicate steps were lost BEFORE you find out after the thing runs into a wall.

I'm genuinely curious about your implementation. These systems are new to me.

Update: I believe the issue was the external driver had a default amp setting of 8A, and the stepper motors I was using were only 2.0 A. When I finally was able to get into the external driver firmware (pro tip: order the RS232 compatible cable AND a serial-to-USB from amazon or something), I could toggle the amperage setting from 8A to 2A and create or turn off the vibrating motor issue I was experiencing.

With the omc-stepperonline driver and stepper motors, the pulse timing in M569 is set to 7.5. Anything less and the stepping from the motor sounded like grinding. 7.5 sounds pretty smooth.

I often cycle my Duet 2 Wifi's power while doing R&D stuff or messing with the config.g file. Sometimes the IP address will change unexpectedly even though I've been consistently accessing through the same IP for a long time. For example earlier today, the IP switched from 192.168.0.8 to 0.9.

A lot of the time I'll guess a nearby number and it will work. Sometimes I have to ask the Duet through M552 what the new IP is (connect directly through USB, as described below).

If you lose DWC access, you can connect your computer to the micro USB port and use terminal / yat to communicate with the Duet over serial port. This is like Step 3 of the Getting Connected walkthrough: https://duet3d.dozuki.com/Guide/1.)+Getting+Connected+to+your+Duet/7

You can check to see if the Duet (Wifi) is connected to Wifi by looking at the blue light on the Wifi module. If the light is on, your Duet is still connected to Wifi but at a different IP address. Sometimes mine will disconnect and I have to power cycle. You may need to set the Duet Wifi connection up again - just follow the link above.

@joergs5 ah, thanks for pointing that out. I have the T parameter in M569 set to T10 right now - I saw a post from dc42 that said it would limit the step rate, but otherwise cause no problems. I'll leave it there for now to make sure all other things are working, and then decrease the timing later.

Regarding acceleration / speed, this is just with the motor sitting on the table, no load, and only commanding +1 mm movements. Acceleration and speed shouldn't be a factor yet.

@joergs5 If this were the issue, wouldn't it have worked when I wired all of the + leads to +5V?

@joergs5 , the external driver has a dip switch for

"SW5, Motor DIR: off=CCW or on=CW"
"SW7, Pulse Mode: off=PUL/DIR or on=CW/CCW."

I currently have it set to PUL/DR and CW to align with the Duet firmware "Forward." (This makes more sense to me than CW aligning with Backward).

@sean, as a follow on. ENA+ is by default at 3.35 V.

If the schematic above says >3.5 V, would 3.35V be an issue? If it were, I would imagine wiring all the + leads to 5V would have remedied my issue.

I am also having issues getting my external drive to work. I attempted to wire the
+(STEP,DIR,EN) to the 5V on the Heater Pins on the expansion, to see if the voltage of the expansion breakout was too low. This did not change my stepper motor behavior (it just vibrates after a few X+1 commands.

See thread here for more information: https://forum.duet3d.com/topic/7703/closed-loop-control-of-stepper-motors-with-rotary-encoder/24

@joergs5 That approach makes sense - my hang up is that i don't know if the settings on the Duet are matching the dip switch settings on the external driver. Questions like fwd v. CW, or Pulse edge rising v. falling, etc.However, I will mix & match drivers w/ motors to see if the issues are consistent.

I don't believe ALM has any bearing on the issues I'm facing. The ext. driver has a flashing LED that tells me when there is an issue, so the ALM connections are just to notify you elsewhere, such as activating a trigger on the Duet as @dc42 points out in the post you linked.

@sean I followed the steps on this post, to see if the voltage coming from the expansion breakout was too low for my ext. driver. I didn't suspect so, and it didn't change the behavior of the motor.

@joergs5 Thanks for the response. I adjusted my R parameter in M569 to R1, active high, and the motors seem to stay cool.

@sean Based on this diagram from the driver data sheet:

I updated my M569 command to:

M569 P5 S1 R1 T2.5:2.5:5:0

On the external driver I have the Motor DIR set to CW, and the S1 parameter in M569 set to "Forward" because that seems to make sense.

R1 set to Enable High, because enabling the driver from the chart looks like a high command.

And the Step Pulse timing seems to correspond to:

Taa:bb:cc:dd (firmware 1.21 and later)
aa: Minimum driver step pulse width, t3
bb: step pulse interval, t4
cc: direction setup time, t2
ddL direction hold time, 0

This is still causing my motor to vibrate after 1 or 2 X+1 commands.

@dc42 I received the external driver and expansion board. I have not had any luck getting it to work so far.

Driver = https://www.omc-stepperonline.com/index.php?route=product/isearch&search=CL57T

Motor= https://www.automationdirect.com/adc/shopping/catalog/motion_control/stepper_systems/dual_shaft_and_encoder_stepper_motors/stp-mtr-17048e

Setup=
(Driver) to (Duet Breakout) on Drive 5
PUL+ to STEP+
PUL- to STEP-
DIR+ to DIR+
DIR- to DIR-
ENA+ to ENA+
ENA- to ENA-

From my config file:

; Motor Remapping
M584 X5 Y1:2 V0 U3 Z4;

; Drives
M569 P0 S1 ;
M569 P1 S1 ;
M569 P2 S1 ;
M569 P5 S1 R1 T2;

M906 X2000 Y2000 Z0 U0 ; Set motor currents (mA)

The stepper motor has encoder feedback, so first I connected only the stepper motor wires (A+/- B+/-) to the Duet and commanded the stepper motor just fine. When I plug the stepper into the external driver, I noticed that the stepper motor gets hot (about 55+ C) after 10 minutes. That seems to be too high (also data sheet says- 20 to 50 C). I checked the amp setting in M906, and you can see its 2A, as suggested in the motor spec sheet.

For the dip switch settings, SW1-SW4 are simple, they just control the encoder resolution (set to default for now). SW5 to SW8 though, I am having a hard time understanding their connection to the config.g settings under M569. In the GCode documentation it says "backwards" or "forwards" for the S parameter - how does this relate to CW or CCW as the Driver seems to indicate?

Currently, with the dip switches all set to OFF, I have (on the ext. driver)
DIR=CCW,
Auto Tuning = Yes,
Pulse Mode = PUL/DIR, and
Pulse Edge = Rising

When I command a X+1 movement from DWC, the shaft seems to click forward, but if I do it another time the movement isn't the same, and a third X+1 causes the motor to vibrate erratically.

Any guidance you can provide would be greatly appreciated!

@danal I wouldn't say "won't fix" because when we deploy our product it will be difficult to service without incurring a lot of costs (travel or shipping, as an example). Closing the loop on the motion system is peace of mind to know that the duet and external driver are working together to maintain the expected position. And then when something off nominal happens, like a loose belt, or a bit of zip tie, or w/e pops up in the environment, the external driver's fault feature will allow us to shut the machine down before it damages itself extensively.

Absolutely appreciate the question, and it is a good point to remind us that the external driver doesn't solve design flaws or assembly errors that may lead to an issue. We still need to be conscious of our choices there.

@aj-quick said in Closed Loop Control of Stepper Motors with Rotary Encoder:

I suppose the driver you linked will work. The servo will complete its movement when the system stops sending step signals. It will be the same as a stepper motor.

You can hook up the feedback trigger for error into the e-stop for that particular axis and then setup a trigger to run code when the servo error is triggered though. So if for some reason the servo is unable to complete its motion (stuck motor for example) it will send an e-stop signal.

Based on @dc42's response below, that seems to be the case. The error catching will be enormously helpful. I ordered the part I linked and will get it next week.

@dc42 said in Closed Loop Control of Stepper Motors with Rotary Encoder:

That should work with the Duet, although you will probably need to use the expansion breakout board to boot the output current for the step, direction and enable signals.

We have already reached out to Roland to order the breakouts. Though he did direct us to this post: https://forum.duet3d.com/topic/1501/duet-expansion-header-breakout/9. I am hoping the appropriate R setting in M569 will remedy any issues.

We currently use the M400 command to identify when the last G1 command has finished (add M400 after G1 ... so that the "ok" from M400 doesn't respond until G1 completes, given that we are under Marlin compatibility mode).

@dc42, with the external stepper driver, will we see the same type of behavior from the Duet? Meaning, if we use the breakout to send the logic commands to the external driver, will the Duet know when the move has completed and send the 'ok' back only after the desired position has been reached?

What happens if there's a missed step (the entire reason for the closed loop system), will the Duet lag behind and send off the next command?

@aj-quick What about option that I linked? It also does the all-in-one w/ the appropriate stepper motor (that has encoder included) and expansion header from the Duet.