why does this happens?

Hi I retrofitted a weeke BP10 and it is working fine but I have 2 issues.

some times it has sudden accelerations and it gets a following error and it stops
how I can solve that problem, a better PID tuning would help? acceleration parameters? it only happens on the rapid movements never on the working movements.

also the second issue is that when it stops I can just do a run from here so it will start where it stopped before and it will finish the work just fine, but sometimes it get a rounded corner where it has supposed to be a 90 degrees, it only happens if I do a run from here command.

What do you have set for your FERROR and MIN_FERROR in your ini file?
If you set them for different values, with the min one smaller Linuxcnc will use the larger at the axis' fastest speeds and the smaller MIN_FERROR will be the limit at slow speeds, and in between Linuxcnc will interpolate between the two. Perhaps you need to set a larger FERROR. (or improve your servo tuning.)

Your 2nd problem, is because when you restart a file from a line you are probably missing where the G64 Px path blending tolerance was set in the preamble of the file. Using run from a line is dangerous because this and any other important configuring codes used earlier in a file will not be set.

I had not have aces to the machine on the las weeks so I could not check but I went this morning and the MIN_FERROR is 1 and FERROR is 10 I changed to 20 and left the MIN_FERROR with 1 and I could not make it fail again under any means.
I don't know if that is a safe value for that but I will leave with that until I get a better servo tuning

I have checked the cable and we had an issue before with that axis and it was a conector not properly fitted this error was after that and I checked the encoder signal with an oscilloscope on all axis.

and the G64 from the MIDI is actually a pro tip thanks it will be a really useful.

If you had you ferror set to 10, asuming a metric machine, that is a whole cm of following error. that is quite large. If your exceeding that then there is a problem somewhere. Places I would look first is to make sure that maximum acceleration and velocity settings are within the capabilities of the hardware. If Linuxcnc is commanding a motor to go faster than it can all sorts of bad things such as you describe can happen. What does a Halscope trace of vel-cmd, vel-feedback, f-error look like for a move at max velocity?

I did not know that number were cm so that is a really bad thing.
yes it is a metric machine.
I will get to the machine tomorrow and check that but I tried lowering the acceleration and speed before but I could not get it to work very well, but I will try lowering it even more.

No, it is in mm (10 of which = 1cm).

ah better I read your answer in a rush I will do the test tomorrow but I think it is becase as you mentioned the acceleration and max velocity is outside hat the machine can actually do. thanks for clarifying.