> A real time host is still needed for CNC coordinated motion with Ethercat 
> slaves. Ethercat does no change this at all. Laptops will work in some 
> circumstances but can cause troubles with multiple ms real time delays 
> when doing power management tasks.

A smart device could figure out the correct point in time then it should happen 
to drive the operator crazy or else Murphys will help.

> Also RPIs are not good real time Ethernet masters for a couple of reasons
> 
> 1. The Ethernet is routed through USB which has terrible real time 
> characteristics

USB is fast but in practice I guess the extra USB layer in between Ethernet do 
nothing good for the real time charteristic.

> 2. The RPI is too slow to have decent real time network performance with 
> Preempt-RT

Might be but I think it's fast enough if not interrupted by something else.

> As far as LinuxCNCs architecture goes, keeping the real time portions of 
> motion in the host are required to retain the power, extensibility, and 
> flexibility of HAL, You can of course move HAL to a remote ucontroller that 
> supports floating point and dynamic object loading, but then you have two
> OSes to maintain rather than 1.

Tow OSes is certainly a drawback but I guess it would also be possible to 
connect user interface via ordinary network or run without GUI.

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