Hello,

"and 8 LEDs as out out. "

Watch out for the maximum drive of the MCU particularly when all the LEDs are ON - not a good idea to drive LEDs directly in such a case. Use some driver / buffer in between and save the MCU before it is too late.



"Let us assume that:-.
A motor is to be started with main contactor K. K is energized through safety
relay K3. Safety relay K3 is energized through relays K1 and K2.

Is it Ok ?"

If its OK with you its OK by me!! YOU are the best and the only master of YOUR design.

Raghu