Random E-Stop with CNC12

1

Hi Everyone! I’ve come across several times where CNC12 suddenly estops for no apparent reason. For instance, last night I left my machine on (not cutting) and at 6:59 PM it said “406 Emergency stop detected”, as seen in the msg_log.txt:

(1) 06-10-2025 18:56:37 406 Emergency stop detected
(1) 06-10-2025 18:56:37 490 Reset Initiated, Press Reset to Clear
(1) 06-11-2025 8:58:17 Created Weekly Report
(1) 06-11-2025 9:03:32 204 Exiting CNC…Normal Exit (66)

I came in this morning at 9AM, and it was in e-stop state. It generated a weekly report too. Restarting CNC12 didn’t fix it. I had to quit CNC12 and power cycle the Centroid Control Box to get it out of this state.

I looked at the Inputs and nothing was tripped. Cycling my e-stop button would show it activate and de-activate in the PLC Diagnostic Screen.

Screenshot 2025-06-11 090225
Screenshot 2025-06-11 090225986×393 17.2 KB

Is there anything else I can look into to figure out why this happens?

Thanks,
Corbin

2

Did you PC go into power saving mode by any chance?

Maybe there’s some loose wiring somewhere in your E Stop circuit? It’s a normally close circuit so any break in the connection will cause an E Stop… you could pretty easily suss that out by powering up and wiggling all of the wires…

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3

I’ve got all the power saving stuff turned off via the tuner.

I don’t think it is the e-stop circuit; the PLC Diag’s would show it, and resetting the e-stop doesn’t help. It’s super strange that a reset of Acorn makes it okay, without anything else changing.

I’ve had this happen twice (maybe three times), and it is sort of random. Other times I leave my machine on for days without touching it and no problems.

Corbin

4

Do you have cats? Maybe they’re walking over something that trips it?

5

That is a good thought, but no cats inside the shop! It is also strange that I can’t reset it without rebooting the controller.

6

this is odd… I leave several machines on for weeks on end… I’ve never seen this. I even have one PC that I let go to sleep (just to see what happens) and it still stays connected and doesn’t go into a reset state…

Does this ever happen while running a job, or just when the machine sits idle?

7

Here’s something you can try Corbin:

Unplug your E Stop from the control box (the M12 connector at the bulkhead)

Then go into the PLC diagnostic and override your E Stop to be always on. If this is a software/PC fault then in theory this should happen again.

If it doesn’t it’s hardware.

**To anyone else reading this, DO NOT override your E stop this way! :wink:

8

I may have had the same thing happen once as well. It is similar in that it said “406 Emergency stop detected” and I needed to power cycle everything in order to clear the fault.

The difference is I was in the middle of a cut. Since it only happened once I was assuming something caused me to miss a step and it stopped itself. But that assumption is purely pulled out of thin air. I actually have no idea what happens when a step is lost on the servo system.

FWIW after the power cycle I re-ran the same gcode and everything worked as expected.

9

You’ll see a “9031 Drive Fault” in the message box when that happens

10

Thanks for the clarification. I guess I definitely didn’t miss a step then.

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It’s so sporadic, that it might not ever happen again for a long time. I need to narrow down more specific steps that reproduce the problem, and when I do that I’ll give this a try.

To answer the other questions: In the 7 months since I’ve been on Centroid, I’ve seen it three times. Twice it happened when the machine was idle overnight, and in the morning it wasn’t responding and had the error. Once it happened when I was jogging the machine..or I was starting/restarting a program…I can’t quite remember, as I just restarted the box and it worked again without a problem.

I started a thread on the Centorid forum to see if their experts have any advice.

12

Was your machine up and running for a long time before it happened (ie: days/weeks?) Were you running really long g-code files?

I’m trying to find some pattern.

Corbin

13

Yes, I usually leave the machine running for ~10 days at a time.

This time the GCode file was only ~6K lines. I’ve used much bigger files in the past without a problem.

If it matters I am running cnc12 version “5.22 r0 u1”, and I am using the ATC code from your github as of January. I think there has been an update since then, but I haven’t changed since everything is currently working great.

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14

The people on the Centroid forum noticed that OUT7 (my “NoFaultOut” output) is red, when it should be green. So something else is causing a fault from the Acorn board. What other things can I look into to find out what would cause that fault? (When it happens again)

15

I read through the PLC source. I have some ideas on what I can look into the next time it happens.

16

Your VFD turning off would put it into a fault state if you have that option enabled.

17

I do have that setting turned on, but think I would have seen a “9030 SPINDLE FAULT!” in the log file, and I don’t see that. I also tested this; turning the spindle box on/off and seeing if I could get it into this bad state, but I can’t reproduce the problem.

When reading the source, I have a feeling it is one of the other states that is set:

IF !EStopOk_M || PLCFault_M || SV_STALL_ERROR || SpindleFault_M || LubeFault_M ||
AxisFault_M || ProbeFault_M || OtherFault_M || DoorShutDownStop_M || THCError_M
THEN SET SV_STOP

When it happens again, I will use PLC Detective to figure out what one is set, and that will give me something else to look into. Some of the other faults (PLCFault_M and OtherFault_M) don’t ever seem to get reset except on the initial reboot…so I have a feeling it is one of those bits that is enabled. It might be months before this happens again, but now I have something to look into!

18

Let me know what you find!