I guess i am still skipping on how real time kernel address the pause? it just never pauses or it no longer needs to be paused?

When hardware has data ready for a program it generates an interrupt that lets the OS know that there is data ready for an application. My understanding is that real-time OSs give high priority to interrupts so that they’re processed quickly - usually within a fixed period of time (e.g. they may have a max time between interrupt and processing).

as a side note, is this similar technology they use in high precision manufacturing?

In those cases it may be more likely they use a micro-controller that doesn’t run any OS at all - at least not a multi-tasking one. If you’re just running a single program you don’t need to worry about latency due to other applications running.