I am scared that my question is quite basic and stupid. However, the robot is expensive, so I don’t want to take a risk.
In fact, I would like to start and stop the program using DI, as presented in this topic How to restart after "HALT". Could I directly connect a DO to a DI of my UR to archive the goal?
Yep. I do this all the time for various things such as using the Teach Pendent to toggle Free drive on/off. Don’t know your exact use case, but if you’re using a DO from the pendent to start/stop the program, you should also just be able to hit the big Start and Stop buttons. But If you’ve got your reasons for wanting it, more power to you.