"Attempt to move the head of a delta printer before homing the towers"

I've been using the Duet 0.6 for the last few months, and have really been enjoying it.
Then, last week, I started having issues of my ATX supply turning off during a print.

So I swapped the supply.

Now I can't get it to home any more. When I send the home command, I receive:

Quote

Attempt to move the head of a delta printer before homing the towers.

I've upgraded to the latest 1.13 beta firmware (was on 1.12), and have tried communicating both via the web GUI and via USB.

All of my endstops seem to work--I can press them and watch a corresponding light on the board.
My hot end and heat bed still heat up as well.

Any ideas?

1.13beta1 is working on my delta. Do any of the carriages move at all when you try to home the printer? What do you have in your homedelta.g file?

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

The problem began with 1.12, so I'm not thinking 1.13 is suspect at all.
I'm fearing I've had some hardware failure.

And no, none of the carriages move at all.

Here's what's in my homedelta.g:

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; Homing file for RepRapFirmware on Mini Kossel
G91 ; use relative positioning
;******* Change F250 in the following line to F2500 when you are finished commissioning
;******* Change 320 in the following to a higher value if your Kossel has taller towers
G1 S1 X420 Y420 Z420 F10000 ; move all carriages up 420mm, stopping at the endstops
G1 S2 X-3 Y-3 Z-3 ; move all carriages down 3mm
G1 S1 X6 Y6 Z6 F250 ; move carriages slowly up 6mm, stopping at the endstops
G1 Z-5 F2000 ; down a few mm so that we can centre the head
G90 ; back to absolute positioning
G1 X0 Y0 F5000 ; centre the head and set a reasonable feed rate

That file had been working fine for me up until the power supply failures began.

Test whether you can move individual motors, by sending G91 followed by G1 S2 commands. For example, G1 S2 X10 should move the X carriage up 10mm.

Also use the M119 command to check that the firmware is reading the endstop switches correctly.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

M119 works fine.

But G91, followed by G1 S2 X10 reveals no movement.

Same for G1 S2 Y10 and G1 S2 Z10

And I see no movement on the extruder when I heat the hotend and use G1 S2 E10

After further investigation, I've discovered an intermittent connection on the ground within the "5V standby" lines to my ATX supply.

I don't think the Schottky diodes would allow that to spike a negative voltage or anything, but at this point I'm betting that something has fried the drivers.
I'll probe some lines on the board tomorrow.

I would be very surprised if you had fried all the drivers. Have you run M906 with no parameters, to check that the motor currents have been set?

Another possibility is that the digipot chip or one of the components associated with it has developed a fault.

Edited 1 time(s). Last edit at 06/01/2016 10:11AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I've checked the ref voltages and used M906 to change them, which seems to work.
X-ref is a lot lower than the others. With M906 800 I see ~.4V on most, ~.1 on X.

When I get back to the printer today I plan to check if I'm seeing activity on enable and step.

Quote
maso
I've checked the ref voltages and used M906 to change them, which seems to work.
X-ref is a lot lower than the others. With M906 800 I see ~.4V on most, ~.1 on X.

When I get back to the printer today I plan to check if I'm seeing activity on enable and step.

By my calculations, you should get 0.64V with 800mA set.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

You're right--I'm reading 0.66V with 800mA on all but X. I was going from memory when I said 0.4V.

I can verify that when I first power the board on, the enable(not) lines are HIGH.
I press the "HOME" button, then quickly trigger all 3 endstops manually, and the enable(not) lines go LOW (and the firmware registers a successful HOME, so now we know why that "Attempt to move the head..." error was there).

But the motors never move, and have no resistance when enable(not) goes LOW.
It's surprisingly difficult to probe the Step line, so I'm not worrying about it. Shouldn't matter without the drivers getting actually engaged anyway.

But this is interesting: the reset(not) and sleep(not) lines measure 0.7V, in spite of the 10K pullup resistors.
I shorted that 10k with a pair of tweezers (while motors were enabled) for grins, and it didn't seem to change the motor resistance at all.

I measure 12V on C32, 5V on C30, and 3.3V on R38, so I think voltages are good.


@dc42, many thanks for your diligent help. And if you've got any other ideas that might revive this, I'm all ears. But I think it's time for new hardware.

As a follow-up:

I got a new Duet board and replaced my old one. Everything works great again!

I don't know what failed, but it appears to have been a hardware issue, not a firmware one. The original error "Attempt to move the head of a delta printer before homing the towers" was due to the motors not moving at all, and the home process timing out without triggering the endstops.

Quote
maso
As a follow-up:

I got a new Duet board and replaced my old one. Everything works great again!

I don't know what failed, but it appears to have been a hardware issue, not a firmware one. The original error "Attempt to move the head of a delta printer before homing the towers" was due to the motors not moving at all, and the home process timing out without triggering the endstops.

Are you sure it wasn't a 12V power issue - perhaps as simple as the screws in the power input terminal block no longer being tight?

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].