Make all slave Arduinos listen on the input where that signal line is connected. On a rising/falling edge (whatever you prefer) store the current value of millis(). From now on our time reference is millis() - stored_value. Voilà, you have them synchronized.
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Sorry, but I don't get it. What is the signal line? Do you mean the clock line?
And every arduino will store its own millis on a falling (or rising) edge? How would that make them synchronised?
What are you using?
If I can synchronise different arduinos , I'll be using the same board : arduino uno.
How are the original sensors (the ones you're trying to simulate) synchronized?
The sensors I am trying to simulate are not synchronised, since every sensor has its own data (analog data conerted to digital) so it is able to respond to the master anytime.
In my case arduinos are not sensor and do not have captured data. So I'll make them read log files (containing that data) and this should be done like in the real network.
How many sensors are typically in that network?
The number is not fixed there can be many sensors (up to 30)
But it would be fine if I can simulate from 10 to 20 sensors.