24
RS-232 TO FIBER OPTIC MULTIPLEXOR
CAUTION!
Do not look into the transmitter. Prolonged exposure to high-intensity
infrared light will cause eye damage.
3. If both optical transmitters appear to be operating and only one SDCD
LED is OFF, reverse the fiberoptic cable connections at both ends of the
cable. That is, connect the fiber that was attached to each mux’s
transmitter to its receiver, and vice versa. If the SDCD LED that was OFF
comes ON and the other one goes OFF when the connections are
reversed, this definitely isolates the problem to one fiber of the cable. The
cable will have to be replaced. If there is no change in the state of the
SDCD LEDs—the one that was OFF stays OFF and the one that was ON
stays ON—go to Step 5.
4. If both SDCD LEDs are OFF, try testing the two multiplexors with another
fiberoptic cable, if one is available. If the problem goes away when you use
the replacement cable, the old cable is faulty. If the problem remains, or
if no replacement cable is available, proceed to Step 5.
5. Test the muxes’ ability to communicate without cable. The multiplexors
can transmit to each other optically through the air over very short
distances (not more than 2 to 3 inches [5 to 7.6 cm]). Place the two
multiplexors on a flat surface with the rear corners facing each other and
the optical transmitter and receiver connectors pointing toward each
other, at a distance of approximately one inch (2.5 cm). If the muxes’
SDCD LEDs don’t come on immediately, slowly slide one mux toward the
other, keeping the optical connectors aligned, until the LEDs of both
muxes come ON. If this happens, it should be possible to transmit error-
free between the multiplexors using any of the tests described in
Section
5.3
after you move the muxes a little closer yet. If you achieve error-free
transmission through the air, proceed to Step 6. If both LEDs don’t light
or it remains impossible to transmit data without errors no matter how
close together you push the multiplexors, there is probably a problem
with a transmitter or receiver. See
Section 5.7
for instructions on shipping
the muxes for repair.
6. If the multiplexors can communicate error-free through the air, but not
through your original fiberoptic cable or any replacement cable you try,
the problem is probably in a transmitter or receiver, but will require an
optical power meter to pin down. If you can obtain one, try the procedure
described in the third paragraph of this section. If you can’t, call us for
technical support.
