The LDM80 is a small,
inexpensive fiber optic
transmitter/receiver completely
powered by the host
RS-232 port. The enclosure for
the LDM80 is a conductive shell
which greatly reduces RF
radiation and susceptibility. The
rugged metal enclosure is small
enough to mount on the back
panel of typical computer
equipment saving valuable desk
and floor space.
A pair of these
units allows most RS-232C
cable links to be replaced and
extended with a duplex fiber
optic cable. The normal 50-foot
RS-232 limit may be extended to
2.2 miles (3.5 km). Fiber optic
data communications provide
complete EMI/RFI rejection,
isolation, elimination of ground
loops, and reduced error rates.
Data security is enhanced by
almost nonexistent
electromagnetic emissions. The
RS-232 connection is through
male or female EIA 25-pin
connectors. The fiber optic
connection is either through
SMA (905) or ST connectors.
The LDM80 is equivalent to a
3-wire, full duplex, RS-232
circuit. Handshake signals are
locally connected (see Figure 1. on PDF)
Indicating LEDs come on during
a "SPACE" on transmit or
receive data. A TD/RD reversing
DIP switch is provided for
connection to DTE (Data
Terminal Equipment) or DCE (Data Communication
Equipment) ports. The LDM80 optical transmitter
may be used with a wide range
of fiber sizes. Specifications are
for 100/140µm. Other fiber sizes
may be used with a resulting
different cable loss budget.
