I have a Chinese laser machine (CO2 6040 with M3 nano board) that I cannot get to communicate with my laptop.
I tried every conceivable solution I could think about without success, including:
Any advice?
Let me start with the very basics:
No I am not able to use the machine at all.
No, I am not able to use the machine at all, not with the Coral Laser software (into Coral Draw 11) or any other software
173x141px image is so small and so lacking in detail it is useless. Fortunately, even if it were larger and more detailed, it wouldn’t tell us much.
@d0wnl0rd is the primary developer of Meerk40t, so he knows what he is talking about. You should try his suggestions first.
However, the symptoms you describe could be caused by hundreds of reasons:
We can probably help diagnose this, but only if you start to provide much more detailed information about what is happening - possibly a video (with audio) of your K40 as you power it on and of your O/S screen as you plug in the USB cable might give us more information.
You could / should try k40 whisperer just to see whether this is able to connect to your laser: https://www.scorchworks.com/K40whisperer/K40%20Whisperer%20Installer%200.68.exe
If it can connect then meerk40t should be able to do so as well
Re your pictures: you seem to have a very new m3nano board, that should already be able to support hardware pwm (ie variable laser strength). After you got your machine up and running we might need to amend meerk40t to properly support this - we had an experimental release for that but we did not deploy it, as we couldnt find anyone with a board version that supports it, so you could be our patient zero 
Thanks for your reply.
I will try the k40 whisperer as well and let you know about the outcome.
No problem with being your patient zero. Once I have it up and running you can just let me know what I need to do. In fact I have a spare board that you can take apart ifthat will help.
According to a onetime exchange with the developer of lihuiyu board: “Only M3 and fireware >= 2024.01.18g support PWM. Earlier M3 revisions are just M2+.”
So this older board would not provide the required functionality.
Hmm, that’s not a good sign, the ch341 should be recognized. The board might be dead, faulty cable?! Have you tried it with another machine? Does the laser power up properly at all (including a short movement of the motors), if yes, can you control it somehow via the panel? (I need to admit I am not familiar with your model, so I don’t know whether there is such a feature at all)
I changed the board
I tried a different Laptop
No movement of the motors when switching on.
This model does not have manual controls
If there is no movement of the motors when you switch it on then you definitely have a hardware problem. This is NOTHING to do with your USB cable or computer or Meerk40t - it is your power supply or wiring or controller board.
If I manually move the laser head to the middel of the cutting area and switch the machine on, it returns to the top right all by itself.
Ok - now perhaps we are getting somewhere.
We need detailed photos of your head and the top left and top right corners of the gantry.
My guess is that either:
The m2 nano (and probably the m3 nano) do not connect to USB until it has finished homing.
You guys are FANTASTIC, thanks…
I carefully looked in the corners and found a small cable tie that prevented the head from going all the way to the top right-hand corner. I cut it off and replaced it with one that is out of the way and the machine connects with the laptop when I start it.
THANKS AGAIN TO ALL OF YOU…
