Yes, you are right. It is that I was thinking.
I would like to make a robot with 2 NXT Blocks because I have to use more than 3 motors.
The 2 NXT will run in the same time. When the robot is against a wall the touch sensor is active. The idea is to connect this touch sensor to the 2 NXT to make a pause in the the first NXT program and to oblige the other NXT to make certain other actions while the other is paused.
I could use 2 different touch sensors but it is not really reliable...
Thanks for your answers