How to connect UART of Pi 3 B with a MAX485?


I want to use the integrated UART of my Pi 3 B /dev/ttyACM0
i want to connect it to a MAX485 to control satnogs rotator controller board.
I made a lot of test on a PC with a USB/RS485 adaptor to communicate with my rotator controller,
it works very well, but now i want to use PI 3 B.

Which GPIO of PI 3 B do i have to use to control DE, RE/ of MAX485?
i didn’t found the information on wiki and forum,
although in soft configuration you have example of ROTCTL config HAMLIB_UTILS_ROT_OPTS with ttyACM0 used.

Could you help me?

Thank you.