The current differential function must be "Enabled" for the communications module to properly operate.
The fiber optic modules (7A to 7W) are designed for back-to-back connections of UR-series relays only. For
connections to higher-order systems, use the 72 to 77 modules or the 2A and 2B modules.
OBSERVING ANY FIBER TRANSMITTER OUTPUT MAY CAUSE INJURY TO THE EYE.
The following figure shows the configuration for the 7A, 7B, 7C, 7H, 7I, and 7J fiber-only modules.
The following figure shows the configuration for the 72, 73, 7D, and 7K fiber-laser module.
When using a laser Interface, attenuators may be necessary to ensure that you do not exceed the
maximum optical input power to the receiver.
Figure 3–28: LED AND ELED FIBER MODULES
Figure 3–29: LASER FIBER MODULES
L90 Line Current Differential System
3.3 PILOT CHANNEL COMMUNICATIONS
3.3.2 FIBER: LED AND ELED TRANSMITTERS
3.3.3 FIBER-LASER TRANSMITTERS