Duet sometimes really slow? - I2C error or?

deckingman

@tbs Bit of a long shot but your problem might be the Wago connector - especially if there is any oxidisation of the conductors. You can get two thickish cables in the terminal blocks on the boards so try a cable direct to the Duet terminal block, then a link from that to the Duex and do away with the Wago connector altogether.

dc42

Check that all the screws connecting the ground wire to the Duet and X5 VIN terminals are tight, and check for I2C errors in the M122 report when the problem occurs.

TBS

Thanks for your suggestions!

I will try to remove the wago connectors and solder the cables instead. (The wago connectors were only 6 month old.)
I will replace the cable between the powersupply and the Duet and the Duex5. So I can exclude a cable break.
The screws were very tight. This could not be the problem.

Thanks to deckingman and Mr. Crocker.

TBS

Hello,
I have now implemented your suggestions a few weeks later.

I have changed the following:

The cable to the power supply has been replaced with another 2.5mm ^ 2 cable
Cable length 10.8 cm plus wire end sleeves (about 1.8 cm)
Wiring is as in your instructions
VIN and GND go directly to the Duet Ethernet. From there they go directly from the wire end sleeve into the Duex5
Update to the 2.02RC6

Unfortunately without success! It has gotten worse now. Now sometimes I have the error even if I turn on the Duet.

I've already read this bug including videos in your forum several times. For example:
https://forum.duet3d.com/topic/3735/slowdown-issue/14
Has the reason been found for this error meanwhile?
Is it maybe the Duex5. This was often mentioned in these posts.
Did I make a mistake with the wiring?
Could it be that I have a cable break or loose contact somewhere?

Here is the log with M122:
0_1544922580210_M122_Error.txt

dc42

@tbs, this line in the M122 report:

I2C nak errors 0, send timeouts 25011, receive timeouts 0, finishTimeouts 25010

indicates that the cause is I2C errors. If you are certain that you have fixed the VIN ground connection, then the problem may lie in the ribbon cable.

TBS

The VIN / Ground connection ist correkt.
If it is the ribbon cable, what should I do?

dc42

Replace it.

TBS

Which grid size / dimension do I need for the cable and the plug? How long can it be maximum.

dc42

It's a standard 2x25 IDE ribbon cable connector at each end, 2.5mm pitch pin spacing. The cable I use is 150mm long and I suggest you don't make it much longer than that.

You could try re-clamping the existing ribbon cable connectors in a vice first. Use cardboard to protect the plastic from the jaws.

TBS

Hello,

I replaced the ribbon cable. I have a third time replaced the cables from the powersupply to Duet and Duex5 (11 cm, maximum cable thickness which fits into the Duet socket)

A few longer prints have worked with it. A few days ago, the error unfortunately occurred again.

Procedure:
It was printed simultaneously with Driver 5 and 6 (M567).
Duration of the print about 1 day.
Everything worked here.
After that, the printer has been waiting for 5 hours without turning off.
At the beginning of the next print, the error has occurred again.

Here are the M122 traces:

All 3 traces files have different error messages and show different values (for example in the category: Driver 5: ok, SG min / max not available, Driver 6: ok, SG min / max not available or LaErrors: 694)

How can I solve the problem now?
Should I buy a new Duex5?
Would it be a workaround to generate a power load on all two boards (always turn on all heaters)?
Maybe the cables to the extruders are too long with 2m (E0 E3D Super Whopper Motor, E1-E3 E3D High Torque Motor)?

I have already spent 300 euros on filament for misprints because of this error.

I am urgently asking for help.

deckingman

@tbs I had similar I2C problems but in my case it only happens once every 3 months or so. David (DC42) told me to upgrade to 2.02 final with the comment that the I2C part had been completely re-written between RC4 that I was using and the final release. I note that you are on RC6 but I have been unable to find anything to say when exactly the I2C code was re-written so it could be after RC6. Suggest you upgrade to 2.02 final (DC will tell you to in any case) then report back if you still have problems.

dc42

@TBS, please upgrade to the 2.02 release as @deckingman suggests. However, the major rewrite of the I2C subsystem happened at version 2.02RC6, so in all honesty I don't expect this to change things.

It appears that either something is disrupting the I2C communication between the Duet and the DueX5, or the communication is being lost for some other reason. If we can eliminate wiring issues, then I'll recommend that we try replacing your DueX5.

Please post a photo or photos of your Due/DueX5 setup, that show clearly the power wiring and the ribbon cable.

dc42

PS - in testing the I2C communication at high speeds, I found it helpful to reduce the values of the I2C pullup resistors on the DueX5. The simplest way to do this is to connect a resistor with a value between 1.3K and 2.2k between the TWC and +3.3 pins of connector J13 on the DueX5, and another between TWD and +3.3, like this:

alt text

If you don't have the means to make this yourself, we may be able to send you a ready-made one. If you do make one yourself, take great care not to short the 3.3 and 5V pins together.

deckingman

@dc42 Thanks for that. I'll give it a go on mine. I only rarely get the problem so can't yet say if upgrading from RC4 to final has fixed it for me. I may as well try this mod as well. I think I'll make up a lead that will plug in. Then I can insulate the leads and test it for shorts before I plug it in.

Martin1454

@dc42 Will try to add some resistors to mine - I get the problem about once every 20-ish start - Way fewer than before the new SW, but will see if that gets rid of the last errors. - The 1:20 error is not that much of an problem, but I fear that it will happen midt print (It did in the old SW, but haven't had any longer prints yet with the new sw)

deckingman

@martin1454 If it's any consolation, I've never ever had it happen mid print - only when first powering up. That's even with 30 + hour prints.

dc42

One more suggestion: don't run any stepper motor or heater cables right next to the ribbon cable.

Surgikill

@dc42 Could it just be crosstalk? What if he twisted the power cables going from the Duet to the DueX? I'm looking at a similar setup with ~150mm cables and I'm concerned I'll be having similar issues.

dc42

The length of the power cables shouldn't matter much as long as there is a very short and thick wire between the ground (negative) terminals of the VIN connectors of the Duet and the DueX5, to make sure that the stepper motor currents don't cause the grounds of the two boards to be at different potentials.

It appears that for those few DueX users who encounter these issues, something is disrupting the I2C communications between the two boards. Unfortunately the I2C protocol does not include error detection (other than an indication that no recipient accepted the data) or an error recovery protocol. It could be ground noise causing the disruption; or coupling between the I2C clock and data wires and sources of noise such as stepper motor cables; or something else could be causing the SX1509B chip on the DueX to stop responding.

Surgikill

@dc42 I meant the power cables from the Duet to Duex5. A Low ESR capcitor connected to the power block on each side would probably do wonders to help. I know that in my drones it does quite a bit to smooth out all the noise, and I get significantly more due to the nature of brushless motors. Might be worth a shot.