Hey Howard
This is really important information.

Thank you very much.
If I understood correctly, in fact, you would not need any RS-422 controller, only one HyperDeck acts as MASTER, the 3 cables RS-422 to make the chain to the other 3 units (in this case), so that they follow the same instruction, (PLAY, STOP, RECORD...).
As soon as I can, I will try to do the test, I just need to check the Hyperdeck RS-422 connector PIN OUT .
Thanks Howard.