The diagram shows Sentinel controllers connected in a network. For clarity only three controllers are shown. However up to sixteen Sentinels may be connected in the manner shown.

Notice that the TERM connectors on the first and last Sentinel controllers have shorting jumpers inserted. These shorting jumpers must be in place for correct operation of the network.

The first Sentinel is the master controller because it is the one connected to the host PC. All other Sentinel controllers are slave controllers. The network address of the controller determines if it will be the master or a slave, for information on how to set the network address see here.

For a wiring diagram showing a typical 2 door application see here.