The 23-45x link extends binary functions bidirectional over medium and long distances. For example transfer trip. The link is self monitored and have a local and a remote alarm signal available both as optical indications and a electrical relay output. The local alarm is latched and remote alarm is extended to ensure proper detection. The alarms have to be reset manually.
The 23-45x link is intended to be used for remote trip and or sensing to minimize the need for local controllers. The link is bidirectional for dual side control or sense back confirmation of command. For example a make or brake can be feed back to the controller to verify the command action.
By using the bidirectional signals two units can form a permissive, blocking, or direct transfer trip. The fiber optic media allows for an error free transmission and the self correcting protocol ensures no false tripping.