The Model 561 Transceiver, or slave unit, is used on multi-drop fiber for all remote devices, such as Remote Terminal Units (RTUs), Intelligent Electronic Devices (IEDs), and Power Line Carriers (PLCs). You can arrange up to 250 transceivers in a loop or bus (radial) topology, which allows for many configurations and offers the flexibility to expand your system in the future.

The Model 561-16 Controller, or master unit, is the head end for the SCADA masters. All signals pass through the controller, which can automatically "self-heal" and re-route data in the event of fiber cuts or transceiver failures. Multiple 561-16s can be used for redundancy. The arrangement of transceiver and controller units in a loop configuration provides a highly reliable, fault-tolerant solution.