Slave vs. Master

Every board is a "Master" by default, meaning it want's to start it's GREEN cycle first. When linking multiple boards, only one board can start GREEN.  It doesn't matter which board starts green, so any board can be chosen as the "master".  Therefore, the other board(s) must be set to "SLAVE MODE".

Set as "slave" procedure

Step 1>  Remove power from board being set to SLAVE MODE.

Step 2> With the power OFF, hold down the black TIME SET button.  While holding the TIME SET  button down, apply power to the board and wait two seconds, then release the button.

Step 3> Remove power from board.

If you were successful, the board will power up with the RED light on instead of the GREEN light. 

To set the board back to it's original state as "master", simply follow the same procedure.