MRV Communications EM316SW-XY - Manual (Page 10)

Fiber Driver
®
EM316SW-XY
PN 1288003-001, Rev D2
2
2.1.1 Loopback
Loopback tests and verifies the link integrity. It is available on the fiber optic ports (P2 and P3)
only, and it operates in all four operational modes.
Loopback directs received data on a port to the transmitter to test the fiber optic link end-to-end
from the remote converter.
The figure below illustrates loopback with a pair of EM316SW-XY modules. In the drawing, FO1
and FO2 refer to fiber optic ports P2 and P3.
Figure 1 -- Loopback on FO1 while FO2 is in normal operation
The two loopback switches (loopback and loopback2) correlate to the two converters on the
module. “Loopback” controls port P2 and “Loopback2” controls port P3. The switch settings
apply to operation in all operational modes. In Redundant Link mode, both the loopback
switches must be set to the same position (either both ON or both OFF) for supported operation.