LDM80 - Dataforth
Industrial Data Communication Products
Data Comm.
LDM80
Signal Powered Fiber Optic Modem
Description
The LDM80 is equivalent to a 3-wire, full duplex, RS-232 circuit. Handshake
signals are locally connected as in Figure 1. 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 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 (15m) 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.
Features
• Data Rates to 19.2k Baud at 2.2 Miles (3.5km)
• 17dB Optical Link Power Budget
• Powered by RS-232 Host Port Signals
• Full Duplex Asynchronous Operation
• Indicating LEDs
• DCE/DTE Switch
• Designed for FCC Class A Requirements
• Complies with FCC Class A Requirements
• Connectored Cables Available
• Pinned or Socketed RS-232 Connectors
• CE Compliant
Specifications
Dataforth does not authorize or warrant its products for use in life support/critical
applications.
LDM80
Model
Baud Rate Range
Distance Over Baud Rate Range
Fiber Core Diameter (µm)
100.0 (glass)
50.0 (glass)
62.5 (glass)
85.0 (glass)
200.0 (glass)
1000.0 (plastic)
0-19.2K
Max Cable Length
2.2 mi (3.5) (km)
1.6
(2.6)
1.2
(1.9)
2.2
(3.5)
2.2
(3.5)
98 feet 30 (meters)
Modes
Asynchronous 2-fiber full duplex, 1-fiber simplex
Loss Budget (dB)
17
9
11
16
23
32
Channel Lines
Control Lines(1)
TD, RD
RTS, CTS, DTR, DSR, RLSD
Optical Transmitter
Output from 1m cable
Optical Receiver Power Input for
4µs Pulse Distortion
Optical Connectors
850 nm wavelength
-26dB typ, -27dB min, -18dB max
-44dB min
ST, SMA (905) Compatible
RS-232 Output Voltage with
3kΩ Load
+5V logic 0, -5V logic 1
(1)
DCE/DTE Switch
1
Diagnostic LEDs
2
Power
Port Power
and/or DC operation
+5.0 to +8.5VDC, no current limit, 5mA
>+8.5 VDC, 10mA current limit
Environmental:
Operating Temperature Range
Storage Temperature Range
Relative Humidity
-20°C to +70°C
-40°C to +85°C
0-95% non-condensing
Dimensions
3.57” x 2.1” x 0.74”
(90.7mm x 53.3mm x 18.8mm)
Weight
4.2 oz (119g) max
MTTF
>100,000 hrs
(2)
NOTES:
(1) TD = Transmit Data, RD = Receive Data, RTS = Request To Send, CTS = Clear To Send, DTR = Data
Terminal Ready, DSR = Data Set Ready, RLSD = Received Line Signal Detect.
(2) Ground-benign environmental conditions (no salt atmosphere, <50°C ambient temperature).
SD1070 Rev B
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Industrial Data Communication Products
Data Comm.
Recommended Cables
Installation
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. See Specifications on previous page for cable
diameter, distance, and loss budget trade-off. Fiber optic cables may be ordered
with connectors factory installed.
Power is supplied through a high RS-232 signal, normally current limited,
applied to any of pins 4, 5, 6, 8 or 20. If the LDM80 is powered by a voltage
source, V > +8.5VDC, the current must be limited to 10mA. Voltage sources,
V < = +8.5VDC, will need no current limit. Voltage sources, V < +8.0VDC, will
lower transmission distances. The minimum operating supply voltage for the
LDM80 is +5.0VDC and correct operation below this voltage is not guaranteed.
LDM85CA (1 or 2) Cable
Model
No. of Fibers
Fiber Type
Connector Type
Core Diameter
Cladding Diameter
Outside Cable Diameter
One (CA1) or two (CA2)
Glass
ST, SMA (905)
100µm
140µm
0.12 in (3 mm) each
For installation check-out it is recommended that a short fiber optic cable be
connected from transmit to receive on a locally connected device. See Figure
2 for a typical installation.
Max Attenuation Per Channel
2dB plus 6.4dB/mi (4dB/km)
Max. Installation Load Per Channel
Max. Operational Load Per Channel
67 lb (300 N)
33 lb (150 N)
Min. Bend Radius-Unloaded
1.2 in (3 cm)
Temperature
Operating
Storage
Relative Humidity
-20°C to +70°C
-40°C to +85°C
0-95%, non-condensing
Pin Descriptions
Fiber Optic
Pin 1 Case
Pin 2 TD
Pin 3 RD
Pin 4 RTS
Pin 5 CTS
Pin 6 DSR
Pin 7 SIG GND
Pin 8 RLSD
Pin 20 DTR
[3]
[2]
[7]
[8]
[6]
[5]
[1]
[4]
WARNING! Voltage sources greater than +8.5VDC without current limit will
damage the LDM80!
VDT
Figure 2: Typical LDM80 Installation
Case Ground
Transmit Data
T
Receive Data
Request To Send
Clear To Send
R
Data Set Ready
Signal Ground
Receive Line Signal Detect
Data Terminal Ready
Pin numbers given are for the 25-pin connector with the 9-pin equivalent
in [ ].
Figure 1: LDM80 Block Diagram
For information call 800-444-7644
LDM80
LDM80
CPU
Industrial Data Communication Products
Ordering Information
Model
Description
LDM80-P
Pinned RS-232 connector, SMA (905) fiber
optic connector
Socketed RS-232 connector, SMA (905) fiber
optic connector
Pinned RS-232 connector, ST fiber optic
connector
Socketed RS-232 connector, ST fiber optic
connector
Single-channel optical cable,SMA
Dual-channel optical cable, SMA
Single-channel optical cable, ST
Dual-channel optical cable, ST
LDM80-S
LDM80-P-025
LDM80-S-025
LDM85CA1-XXXX(1)
LDM85CA2-XXXX(1)
LDM86CA1-XXXX(1)
LDM86CA2-XXXX(1)
NOTES:
(1) Specify length to the nearest meter. Example: LDM85CA2-0550 for 550 meters dual cable.
Maximum length available is 1000 meters.
Figure 3: LDM80 Dimensions
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Data Comm.
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