Linking!  How does it work?  What's it for?

"Linking"  is a feature that allows you to connect MULTIPLE boards to create larger, more complex traffic signal configurations. 

For example, if you only have a single 3-light signal such as this one...

...perhaps along with one of these...

...you would not need the linking feature because all that is required to run a signal like this is a single SYNC-5 board that is SELF-LINKED

But if you want to control a 4-way traffic signal such as one of these: or possibly these
...you can LINK 2 boards together to control the two directions.  Thinking about adding a set of turn arrows?  Link a third board!
You can link to your hearts content, as many boards as your application requires.

Thinking about building one of these? (click pic for larger image)    ...not a problem!

How the link connector works

The link connector consists of two screw terminals labeled LINK IN and LINK OUT.  The board normally starts on it's GREEN CYCLE
(see also SLAVE/MASTER mode).  After it cycles through it's RED cycle, it sends a signal out the LINK-OUT terminal, indicating that it
has completed it's three cycles.  The next "linked" board would receive this "signal" on it's LINK IN terminal and begin it's  green-yellow-red
cycle.  Once that board completes it's red cycle, it sends a signal out of it's LINK OUT to trigger the next board, and so on.

You can also have the LINK OUT of one board trigger the LINK IN on multiple boards for some exotic configurations. 

Note:  Once a board has completed it's red cycle, and send it's signal out it's LINK OUT terminal, it will remain RED until it receives a signal
on it's own LINK IN terminal.  Therefore, the last board in the chain should have it's LINK OUT connected to the first boards LINK IN to complete
the loop. Click here for a visual wiring example.