Centroid Community CNC Support Forum

I have been converting a fully functional CNC machine to an Acorn board to gain some additional features.
The goal has been to do it without modifications to the existing machine via an interface board that connects all the existing signals (to and from) the machine to the Acorn board.
I started with Acorn bench test setup using spare components until I had three axes, home switches and estop all working properly.
I then transferred the setup to the machine.
I upgraded to the Pro license to get the ability to software pair the fourth axis in a dual Y axis configuration, not auto squaring.
I added a touch probe and tool setter and flood coolant control.
Everything was working well.
Then the mystery situation began.
The machine will no long home. I went through everything. I did find one bad solder joint in my equipment and repaired it. No change.
I downloaded CNC12 again and did a complete software re-install including all the configuration settings and the firmware update.
I can fully jog the axes in any direction, everything else works as advertised.
I have had CNC12 power up to a state where it says it is homed and has different positions in the WCS display and the machine coordinates display without ever having moved.
I have tried using M106/X P1 F20 to see if the machine will move in that direction and it does. I let it go for a little ways and then cycle stop because there is no home switch on the X+ side, only on the left.
So I tried M105/X P1 F20 and hit cycle start. It goes left for about a quarter of an inch, reverses direction to start going right and then stops after about an inch.
I have tried the Reset Home button on the VCP. It does as littler dance wherever it it is and then says it is homed. Never really travels anywhere.
If it happens to be out in the middle somewhere and thinks it is home it will of course refuse to move in any of the directions that would take it
towards a home switch, so it seems the software limits work.

The pictures and videos are pretty self explanatory.
https://www.dropbox.com/scl/fo/vu520kxp ... 8rk23&dl=0

Please post a report.

Check the Wizard and make sure it is still configured for homing/auto square. If you interrupt the machine during a homing sequence you may need to reconfigure the settings in the Wizard.

Thanks, but not using auto square.

From what I can see your wizard settings look to be setup just fine.
The only thing I really notice in your error log is that there are several 457 Unable to find home errors.
One of which occurred shortly before you generated that report.

Also, the PC you're using doesn't even come close to our minimum requirements.
CNC12 requires a single core rating on the CPU of 1500 at minimum.
Your Celeron N4020 is only at a single core rating of 1137: https://www.cpubenchmark.net/cpu.php?cp ... Hz&id=3683
The following link has some good options for CNCPCs as well as links to the pre configured CNCPCs that we offer:
https://www.centroidcnc.com/cnc_pc_perf ... ments.html

What are you using at home/limit switches and how are they wired?

Will Input1 change its state in the PLC diagnostic if one switch is tripped?

Uwe

"457 ... unable to find home" is often because the control thinks that a touch probe is triggered.

You might want to review your probe, tool setter, and touch plate configuration, and the state of the associated inputs.

To Uwe,

Yes, the PLC diagnostic changes states appropriately for each home switch.

To cncsnw,
Good though. I'll dig into that.

yoda4Acorn wrote: ↑Fri Jun 27, 2025 3:44 pm To Uwe,

Yes, the PLC diagnostic changes states appropriately for each home switch.

To cncsnw,
Good though. I'll dig into that.

also make sure you don't accidently have an input inverted,

easiest way to test marcs suggestion is to remove all the probe related inputs from the wizard and press write settings to cnc control and follow instructions.

Things tried:
Remove all extras like probe and setter. No change.
Change the pc to a full tower system, fast processor, lots of ram, easily passed the performance tests. No change.
Changed the maximum pulses down to 40,000. No change.
I have a new thin client on order.
Love to hear some more suggestions.
Does anybody know where the actual code is for the M91, M92, M105, M106 and M26 routines? I've thought about trying the PLC detective, but I need to know the variables involved in order to set up the detective.

Good news, sort of.
I went back to one of my earliest reports and restored it. Had to tweak some settings, but it finally started to home again, but only if the eStop was programmed for red instead of green. Lots of troubleshooting led to disassembling all of the Acorn stuff.
Discovered that somehow the back side of the Acorn board had become damaged. Mystery solved. I have already emailed Centroid for a replacement board.