You also need to make the diagram clearer. Is it module 1 or module 2 or is it both modules ? I suspect it is both modules but the vertical orange line is the only thing that shows the division between the modules. BUT if it is then there are 5 wires connecting the modules. The only place where there is single wire path is between U6 and U2. If you give a description of how you have designed it to work then you may understand why it does not work. Here is a question that may help you understand why it does not work. How are U6 and U2 synchronised ?