Thank your for your precise answer
my needs are on the industrial side : working with 24v inputs, 24supply, as it is standard in the industry with PLC's like siemens S1200
I have to connect a coder ( it's a Wheel who translate a displacement of a product on a conveyor in pulses..
I will also connect a Product sensor ( work in 24v), and drive a relay for start printing and putting a label on a product
So i have to count pulses : for 200mm i have 1000 pulses, the product move 1m/sec., so i have to count 5000pulses in a second.
Will see if my Arduino is fast enough ( without using interrups ).
I will also communicate with a PC in UDP mode ( send and receive )
i am also intersted on the mechanical format : rail din compatible.
B4R is so much faster to write as PLC langages.
B4R = 2 hours, TIA Portal for siemens = a eternity