The Allen-Bradley 1786-RPFRL module is a ControlNet fiber optic ring repeater module. It supports fiber media redundancy through the use of a ring topology which enables long transmission ranges, protection against electromagnetic interference, and ground isolation between the nodes. The distance between fiber repeaters depends on a number of factors including the fiber quality, number of splices, and number of connectors. For the 1786-RPFRL module, the loss on the fiber links must be less than 15 dB. The total length of the fiber ring is limited by the ControlNet standard to 20 kilometers or less. Plastic or ceramic ST fiber connectors should be used with the module. Metal connectors are not supported.

The 1786-RPFRL module provides 2 fiber channels, status indicators for activity on each fiber channel, and a relay contact connector for system status and communication updates. The power input requirements for the module are 570 milliamps at 5 Volts DC. The power requirements of the backplane are 2.8 Watts (3.02 Watts maximum). The supported communication rate is 5 Mbps. The module can be mounted in any orientation. The maximum voltage for the relay contactor is 30 Volts DC. The minimum and maximum currents for the relay contactor are 1 milliamp and 900 milliamps, respectively. The isolation voltage rating is 50 Volts continuous. The wire size recommended for use with the 1786-RPFRL module is 22 to 14 AWG solid or stranded copper wire which is rated at 75 degrees Celsius or higher. The 1786-RPFRL module is an open module and it complies with T5 North American temperature code. The temperature of the air around the 1786-RPFRL module should never exceed 60 degrees Celsius.