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Fiber Optic A/B Switch with Loopback
The Fiber Optic A/B Switch with Loopback supports separate transmit and receive paths, so you must be consistent when
connecting the fiber pairs to the switch. The fiber optic connectors on the ST version of the switch are marked “1” and “2” to
ensure that the proper connections are made to each port. On the SC version of the switch, the left connector position of the SC
duplex connector for the C port is switched to either the left connector position of either the A or B port duplex connector, and
the right connector position of the SC duplex connector for the C port is switched to either the right connector position of either
the A or B port duplex connector. For example, connect the receive in cable from your shared device to port C connector “1”, and
connect the transmit out cables from your network switches to port A connector “1” and port B connector “1”. In a similar
fashion, connect the transmit out cable from your shared device to port C connector “2”, and connect the receive in cables from
your network switches to port A connector “2” and port B connector “2”.
4. Operation
The Fiber Optic A/B Switch with Loopback incorporates full-duplex optical switch mechanisms controlled by a front-panel-
mounted rotary A/B switch. It is used to share a fiber optic link between two fiber optic networks .
The switch uses a unique optical switching mechanism. When you turn the knob on the front of the switch to select a port,
circuitry activates the optical switch mechanisms causing them to redirect light beams from Port C (the “common” port) to either
Port A or Port B by rotating a gold-plated, spherical mirror. There’s no optical-to-electrical conversion between your fiber optic
links.
To operate the switch, simply turn the knob on the front panel of the switch to route the signals. Turning the knob to position
“A” will route signals from Port C to Port A, while simultaneously looping back signals on port B. Selecting “B” routes the signals
from Port C to Port B, while simultaneously looping back signals on port A.
Because the switch uses latching fiber optic switch mechanisms, if the switch loses power, it will continue to pass signals between
port C and the selected port, while also looping back the signals on the un-selected port.
5. Troubleshooting
If the Fiber Optic A/B Switch with Loopback fails to operate, check the following before calling for technical support.
1. Make sure that the power supply is connected to a power source and to the switch.
2. Check the fiber optic connectors for proper connections to the correct ports of the switch.
3. Operate the switch knob to verify that it’s tightly secured to the switch shaft and does not spin loosely.
4. Verify the integrity of the fiber optic leads by replacing a suspect cable with a spare.
