Advanced Search

It would be very nice to have new forum software. 
Members like Joco have ip ban. This is a very bad situation.

How faster how better.

Maybe JT can give volunteers the 
information to at least setup a new software platform and do migration work.

Now we are all using this outdated nasty
text editor.



 

motmod does create threads, in the sense that "loadrt motmod ......" will create the base and servo threads with the given rates.

Motmod is a component like tpmod.
rtapi creates posix threads. Rtapi does not care about thread speeds. Each posix thread calls a list off components. Then rtapi calls a function order into the component itself with dlopen...

motmod does not create threads.
motmod is a trajectory planner coordinator and supervisor.

 

PCW wrote:

That error (and others I have seen) seem to be a bug in the mesa-modbus code
 

Can you add these to an issue on the issue tracker? 
Just so I don't immediately forget. 

I think that this is a perfectly valid approach, and as you have noted, it was used by Centroid.

The "right" way to do this is probably with a custom kinematics component. That way it is solved by mathematics.

linuxcnc.org/docs/stable/html/motion/kinematics.html

An Arduino is just a board with a microcontroller on it, there's nothing wrong with the Arduino itself. Plus the fact that you can get into much faster microcontrollers with the same Arduino framework makes it alot easier to deal with.

The problem with USB isn't the speed, it's the fact that it has to run in userspace. A USB serial port isn't using a fraction of the speed of USB anyway and the 10/100 ethernet that Mesa uses isn't exactly fast either. USB is always mentioned with this but realistically it could be any serial port. That's where the more productive part of the conversation was going, the fact that a serial port technically can be made to run on the real-time layer. Nobody has ever bothered to make the LinuxCNC component for real-time serial which baffles me since LinuxCNC loves legacy interfaces.

The PC side of this is written in Python anyway, it can't even be real-time from that angle. It'd have to be reworked into a C component. Alex mentioned the Mesa card but a Mesa card for something like this wouldn't be doing anything special that an Arduino can't. The only draw for the Mesa card is the fact that it has a ready to go real-time environment already setup. The Mesa cards intended for use with a control panel aren't even FPGA cards, I believe they run a PIC MCU so hardware wise they aren't really special other than just being well designed.

The best option is a worm gear like 4 axes do. The other option is something similar
www.haascnc.com/service/troubleshooting-...set---ngc-lathe.html

 

 

Is there any chance that this corresponds to something in the kinematics? Maybe an inflection point in one of the joints?