On 1 February 2013 23:45, Gregory Perry <gregory.pe...@govirtual.tv> wrote:
> Can LinuxCNC run as a simple userland process which talks to a hardware servo > controller (such as the Mesa card you mention)? Or maybe more to the point, > is there a standard API with LinuxCNC that will treat a servo control board > as a simple device that it outputs gcode to? As I understand it (and you ought to wait for other opinions) as things stand, the answer is "No". The point is that LinuxCNC as it currently exists handles hardware physical limitations internally. What this means is that the millisecond-by-millisecond servo-thread position updates match the programmed velocity and (especially) acceleration limits of the hardware. Any jitter in the position updates due to the update not being on-schedule is likely to lead to a physical F=ma type problem. To make offline motion control work with LinuxCNC would require a new interface on the gross position command level, rather than the motion control level. This is not how thing currently work, the current LinuxCNC "Way" is for the software to handle all the physical constraints. This requires real-time updates to the hardware, and that means (for example) no USB, There is no technical reason why LinuxCNC couldn't expose a "userspace HAL" for driving external motion-control hardware, but that does move all motion control to the external hardware. There is a cost to this, the external hardware then needs to understand probing, homing, threading, rigid tapping etc, which currently can be used with _any_ hardware. This is not to say that it is a bad idea, just that it needs someone to do an awful lot of work. LinuxCNC +Smoothstepper is technically possible, but it needs someone very dedicated (and thick-skinned) to make it happen. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_jan _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
