Project Ideas Section 12.14.6 in manual

hello

I have read this statement in manual :
"Create an external control panel with buttons, switches, and indicators. Connect everything to a microcontroller, and connect the microcontroller to the PC using a serial interface. "


but in another part of online documentation , i have read that serial communication can not be used for CNC motion control, so what does that above mentioned idea mean?


thanks

User interface has very little need for real time precision compared with motion control. That is why it is ok to use a usb mouse or keyboard with linuxcnc but not to interface with the motor controls.

then do you mean, that the idea of this project is not talking about real time applications?
or may be it talks about connecting the classic ladder (not CNC motion controller) to out side world with microcontroller?

Sorry, but I am not sure what part of what "project" you are referring to.

As an example of Linuxcnc using a non real time USB interface, I have an 8 spindle gang router at work running Linuxcnc. It is using a usb to RS485 serial converter to control the 8 VFDs that run the router spindles. Linuxcnc sends the command to start, stop, change speed... and the VFD returns the spindle at speed signal and other info. Linuxcnc just has to wait for the signals, there are no real time demands on this comunication, so using the USB is ok and it works.