the J1708 standard specify that after 3 bus collisions a random delay must be applied before next attempt.

Now two units, both using the Keil rand(); function, collided. After trying overnight they still collided because the "random" delay was the same for both in all cases. Yes, I know you can seed it, but how do you make identical units running identical code seed differently?

i would say that a pseudorandom like this is nothing but a known string of values appearing to be random. If the lottery was randon by such a function I would be a Millionaire.

Erik