Gary:
I guess I forget that most of you dont really know whats under the bonnet. Smoothsteppers, printer ports, most controllers are fed motion in waypoints. The printer port was fed 200uS points, the rest are almost all 1ms waypoints. So the controller, m3, m4, linux..whatever, take in the Gcode, they hold the state engine which is the guts of cnc. They interpret the Gcode , control the various states, then plan the trajectory to 1ms waypoints.
Motion engines are told whats up for the next 2 seconds or so, the controller makes sure this 2 seconds is extended as it depletes. The controller
takes care of acceleration, mixing speeds between axis, maximum and mixed velocities , offsetting, and toolpath displays. Scripting and configuration as well.
Engines take the waypoint data, and are programmed to take a step count for each millisecond of motion, how many steps each axis takes in that ms
determines end velocity and such. So jerk constraints,acceleration curves and constant velocity and so on are computed by the millisend and continuously sent to the device. Its all a complex dance of internal motion before the motion engine gets sent its data. How smooth the motion is, how complex the logic and scripting can be, thats all controller, the actual steps are made by the engine.
Im not saying the controller is more important than the engine, there is a certain chicken and egg flavour there.. I just wanted to clear up
that the engine itself doesnt even come close as yet to replacing the controller. Its been tried many times to do so, to have usb sticks with the programs on them plugged into a board and away you go.. .. its always failed, for various reasons. That day IS coming, but it isnt here quite yet..
Over the years Ive been told many times by people that hardware will replace the controller, the ncPod, the "Brain", and a few others had tried while I was still making Mach3. They all had truly planned to do so.. but its only when you try to actually write a controller you find just how vastly complicated
it truly is. Mach4 was supposed to be ready years ago, and I suspect theres a few humbled ego's from the experience of bringing it to where it is today.
Mach3 is far from perfect, but replacing it has proven a hurculean task.. which when you consider its age..is a real testement to its abilities, and the large group of contributers to its growth.
Art
Art