Duet sometimes really slow? - I2C error or?

dc42

@deckingman, if they went up that much then I suspect they were continuously incrementing.

What I suspect happened is that the interrupt signal from the SX1509B on the DueX went high, indicating a change in an endstop input signal (real or imagined). That causes the Duet main processor to try to read the SX1509B input registers, which will also make the interrupt signal go away. But if I2C communication with the SX1509B has broken down, the interrupt won't go away and the Duet will keep trying to read it - which accounts for the slowdown.

deckingman

@dc42 Cheers. I'm just in the process of making up a plug with the resistors you mentioned elsewhere. I'll try that and I'll replace the ribbon cable between the Duet and Duex5 as well. Open to any other suggestions.

dc42

@deckingman said in Duet sometimes really slow? - I2C error or?:

@dc42 Cheers. I'm just in the process of making up a plug with the resistors you mentioned elsewhere. I'll try that and I'll replace the ribbon cable between the Duet and Duex5 as well. Open to any other suggestions.

Please try just the resistors. The ribbon cable is unlikely to be the problem, and I'd like to know whether the resistors fix it.

deckingman

@dc42 said in Duet sometimes really slow? - I2C error or?:

@deckingman said in Duet sometimes really slow? - I2C error or?:

@dc42 Cheers. I'm just in the process of making up a plug with the resistors you mentioned elsewhere. I'll try that and I'll replace the ribbon cable between the Duet and Duex5 as well. Open to any other suggestions.

Please try just the resistors. The ribbon cable is unlikey to be the problem, and I'd like to know whether the resistors fix it.

Sure thing - will do.

Martin1454

I will try the next time it occurs to plug on my logic analyzer and see what I can see.

deckingman

@dc42

Had to improvise a bit (as well as make allowances for my failing eye site and shaky hands ) but it'll do the job. The resistors are 1.8K so pretty much in the middle of the range you specified. We'll see what happens....

Interestingly enough, now that the machine is not in an error state, those switches that are connected to the Duex End stops do now respond, even though the axes they were originally assigned to are no longer configured - (I guess you knew that though).

deckingman

@dc42,

David. As I'm waiting for some filament to arrive, the machine is just sitting here idle. Is there anything I can do to attempt to provoke the misbehaviour? I was thinking along the lines of writing a little script that would generate a gcode file that simply toggled one of the duex5 fans on and off. Or may send multiple M260 commands. Is there any point in me doing that?

dc42

@deckingman said in Duet sometimes really slow? - I2C error or?:

@dc42,

David. As I'm waiting for some filament to arrive, the machine is just sitting here idle. Is there anything I can do to attempt to provoke the misbehaviour? I was thinking along the lines of writing a little script that would generate a gcode file that simply toggled one of the duex5 fans on and off. Or may send multiple M260 commands. Is there any point in me doing that?

Yes, you could try that.

GizmotronX5000

@dc42

M122
=== Diagnostics ===
RepRapFirmware for Duet 2 WiFi/Ethernet version 2.02(RTOS) running on Duet Ethernet 1.02 or later + DueX5
Board ID: 08DDM-9FAM2-LW4SD-6J9F2-3S46R-K2XBW
Used output buffers: 1 of 20 (14 max)
=== RTOS ===
Static ram: 25524
Dynamic ram: 98292 of which 0 recycled
Exception stack ram used: 384
Never used ram: 6872
Tasks: NETWORK(ready,544) HEAT(blocked,1232) MAIN(running,3812) IDLE(ready,200)
Owned mutexes:
=== Platform ===
Last reset 00:16:58 ago, cause: power up
Last software reset at 2019-01-23 14:44, reason: User, spinning module GCodes, available RAM 6776 bytes (slot 3)
Software reset code 0x0003 HFSR 0x00000000 CFSR 0x00000000 ICSR 0x0441f000 BFAR 0xe000ed38 SP 0xffffffff Task 0x4e49414d
Error status: 0
Free file entries: 10
SD card 0 detected, interface speed: 20.0MBytes/sec
SD card longest block write time: 15.9ms, max retries 0
MCU temperature: min 31.3, current 31.5, max 31.9
Supply voltage: min 12.0, current 12.3, max 12.4, under voltage events: 0, over voltage events: 0, power good: yes
Driver 0: standstill, SG min/max 37/510
Driver 1: standstill, SG min/max 70/544
Driver 2: standstill, SG min/max 63/552
Driver 3: standstill, SG min/max not available
Driver 4: standstill, SG min/max not available
Driver 5: standstill, SG min/max not available
Driver 6: standstill, SG min/max 0/462
Driver 7: standstill, SG min/max 0/0
Driver 8: standstill, SG min/max 0/0
Driver 9: standstill, SG min/max not available
Date/time: 2019-01-23 15:17:17
Cache data hit count 4294967295
Slowest loop: 59.17ms; fastest: 29.15ms
I2C nak errors 0, send timeouts 63402, receive timeouts 0, finishTimeouts 63402
=== Move ===
Hiccups: 0, StepErrors: 0, LaErrors: 0, FreeDm: 240, MinFreeDm: 237, MaxWait: 181633ms, Underruns: 0, 0
Scheduled moves: 21, completed moves: 21
Bed compensation in use: none
Bed probe heights: 0.000 0.000 0.000 0.000 0.000
=== Heat ===
Bed heaters = 0 -1 -1 -1, chamberHeaters = -1 -1
Heater 0 is on, I-accum = 0.0
Heater 1 is on, I-accum = 0.0
=== GCodes ===
Segments left: 0
Stack records: 1 allocated, 0 in use
Movement lock held by null
http is idle in state(s) 0
telnet is idle in state(s) 0
file is idle in state(s) 0
serial is idle in state(s) 0
aux is idle in state(s) 0
daemon is idle in state(s) 0
queue is idle in state(s) 0
autopause is idle in state(s) 0
Code queue is empty.
=== Network ===
Slowest loop: 63.08ms; fastest: 0.03ms
Responder states: HTTP(0) HTTP(0) HTTP(0) HTTP(0) FTP(0) Telnet(0) Telnet(0)
HTTP sessions: 1 of 8
Interface state 5, link 100Mbps full duplex
The Duex5 endstops do not work as I had previously thought. The endstops on the Duet work, but not the Duex5.
M122 right after pressing the endstops a few times (most lines removed):
M122
Date/time: 2019-01-23 15:18:05
Cache data hit count 4294967295
Slowest loop: 59.10ms; fastest: 0.08ms
I2C nak errors 0, send timeouts 4797, receive timeouts 0, finishTimeouts 4797
No fans are actually connected to the Duex5, so I can't test this. I can configure a dummy fan to the Duex5 for next time though. All fans on the Duet work fine.
M122 (after messing around with duet fans)
Date/time: 2019-01-23 15:22:28
Cache data hit count 4294967295
Slowest loop: 59.11ms; fastest: 0.08ms
I2C nak errors 0, send timeouts 17551, receive timeouts 0, finishTimeouts 17551
No changes. Just sending M122 every few seconds.

M122
Date/time: 2019-01-23 15:23:31
Cache data hit count 4294967295
Slowest loop: 59.11ms; fastest: 29.47ms
I2C nak errors 0, send timeouts 10480, receive timeouts 0, finishTimeouts 10480

M122
Date/time: 2019-01-23 15:24:00
Cache data hit count 4294967295
Slowest loop: 59.10ms; fastest: 29.46ms
I2C nak errors 0, send timeouts 4900, receive timeouts 0, finishTimeouts 4900

M122
Date/time: 2019-01-23 15:24:42
Cache data hit count 4294967295
Slowest loop: 59.10ms; fastest: 29.47ms
I2C nak errors 0, send timeouts 6885, receive timeouts 0, finishTimeouts 6885

I'm assuming the error count starts over each time I send M122. But the number is constantly changing. The lowest I saw was 195 from sending M122 back to back as fast as I could manually from the console. Looks like about 160-170 errors per second on average (164 seems to be the usual) regardless of what commands I send or which endstops I press.

Edit:
I let it idle in this state for about 15 minutes. The average was 166.2 errors per second. It's very consistent.

deckingman

I can add a bit to what @GizmotronX5000 has come with in that I do have fans connected to the Duex5 and that they did not respond to any commands while the machine was in error state (neither did the duex endstops).

dc42

Thanks, you have both confirmed that the DueX5 isn't responding to I2C traffic at all, and the Duet is repeatedly trying (and failing) to communicate with it.

TBS

@dc42: Are there any news about this error?
When does a new release candidate appear?

Thanks for answering.

dc42

For now my recommendation to anyone having this problem is:

Make sure that the wiring of the ground side of the VIN terminals on the Duet and DueX follows our recommendations.
Keep stepper motor cables and other sources of noise at least a few cm away from the ribbon cable connecting the Duet and DueX.
Try adding the extra pullup resistors as I describe earlier in this thread.

The problem I have is that I don't know what triggers this issue.

deckingman

Thus far, I haven't had the problem manifest itself since installing the pull-up resistors. But it's early days yet as the problem only occurs rarely for me. I'll report back in a month or so, unless the probelm manifests itself again. Fingers crossed it won't............

TBS

@dc42 said in Duet sometimes really slow? - I2C error or?:

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:

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.

@dc42: You offered to send me a finished plug. Can you please send me the ready-made one? I can reproduce the error. In the last 6 prints over 2.5 days the error were occured every time. Than we can see of the plug works.
How can I send you my address?

Thanks.

GizmotronX5000

@dc42 I have noticed that the error will start for me sometimes after touching the printer. I do not have ground wires on the casings of my stepper motors right now. Occasionally I will get a static shock and the error occurs. (Can't confirm 100% that this is directly the cause, but it seems possible)

When I am working on the printer it is much more likely to occur than when I am just letting it run.

dc42

@gizmotronx5000 said in Duet sometimes really slow? - I2C error or?:

@dc42 I have noticed that the error will start for me sometimes after touching the printer. I do not have ground wires on the casings of my stepper motors right now. Occasionally I will get a static shock and the error occurs. (Can't confirm 100% that this is directly the cause, but it seems possible)

When I am working on the printer it is much more likely to occur than when I am just letting it run.

Thanks for the information. Static charge is very disruptive of electronic circuits. the question is whether it is causing:

An i2C protocol error, which it may be possible to recover from.
The i2C interface in the Duet main processor to lock up, which it may be possible to recover from by resetting the interface.
The i2C interface in the SX1509B to lock up, which can't be recovered from other than by a reset.

dc42

@tbs said in Duet sometimes really slow? - I2C error or?:

@dc42: You offered to send me a finished plug. Can you please send me the ready-made one? I can reproduce the error. In the last 6 prints over 2.5 days the error were occured every time. Than we can see of the plug works.
How can I send you my address?

Use the Chat facility to send me a message containing your address.

TBS

@dc42 said in Duet sometimes really slow? - I2C error or?:

@tbs said in Duet sometimes really slow? - I2C error or?:

@dc42: You offered to send me a finished plug. Can you please send me the ready-made one? I can reproduce the error. In the last 6 prints over 2.5 days the error were occured every time. Than we can see of the plug works.
How can I send you my address?

Use the Chat facility to send me a message containing your address.

@dc42: It is not possible for me to start a chat with you. Should I send you a Email to info@duet3d.com with my address?

dc42

@tbs, I'll email you.