Page 1
Miniature Modems
Miniature short range modems
offer a simple, low cost and highly
reliable method to connect digital
devices in a local, campus or
metropolitan environment. They
also offer very easy installation
since in many cases they do not
require AC power, but derive their
power from the interface signals.
Miniature short range modems offer the
same communications functions as ACpowered modems but with fewer features,
such as limited diagnostics capability and no
BER tests. Usually they operate over shorter
distances at lower rates (normally up to
19.2 kbps). However, certain modems can
operate at data rates up to 115.2 kbps in
async transmission and up to 128 kbps in
sync transmission. Like AC-powered
modems, miniature modems are designed
to overcome distance limitations of standard
data communications interfaces such as
V.24/RS-232. They also overcome noisy
environments and provide ground isolation.
Miniature short range modems connect
computers, terminals, bridges/routers and
similar data communications devices inside
buildings, campuses or within city
boundaries. They support simple point-topoint communications as well as complex
multipoint campus-wide systems. They also
support flow control when connected to a
printer or a multiplexer.
Typical communications problems, such as
distance limitations and noise, are overcome
by using special signal modulation and line
equalization techniques that allow for
error-free transmission over longer
distances. RAD miniature modems have
transformers to isolate the equipment from
the line and ensure safety. The transformers
are rated at over 1,500 VRMS and are
approved by carriers worldwide for
connection to their lines.
What is the difference between
interface-powered and AC-powered
modems?
Interface-powered and AC-powered
modems perform the same basic
communications functions. Interfacepowered modems incorporate innovative
VLSI and hybrid circuitry that enable them to
consume very little power. These modems
draw power from the interface signals
without loading the adjacent equipment or
interfering with normal operation. For
computers that do not support control
signals, there are special models that derive
their power solely from the data signals.
How do you select the right modem for
your application?
Several factors should be considered when
selecting a modem:
• Computer/DTE interface: V.24/RS-232,
V.35, etc.
• Communication method: sync, async or
both
• Data rate
• Distance
• Media: twisted pair, coax, fiber
• Point-to-point or multipoint application
• Control signals (does the application
require transmission of data only, or also
transmission of one or more control
signals?)
• Environment (is the environment noisy?)
146
A Quick Reference Guide on pages 158-159
will help you select the most suitable
modem for your application.
RAD Data Communications 2006 Catalog
Page 2
MINIATURE SHORT RANGE MODEMS
RS-423/422
converter
4-wire, async
Fiber optic
Fiber optic
4-wire
Elastic buffer
Multidrop
sync/async
56/64 kbps
CMN-16
Elastic
buffer
RS-422
19.2 kbps
Fiber optic
Fiber optic
FOM-6A
SRM-8
SRM-8
SRM-8
High
speed
SRM-8H
IBM 3174
SRM-6AC
FOM-5A
FOM-8
CMN-16
Compact Modem Nest
12
MINIATURE SHORT RANGE MODEMS
• High density modem rack
• 2U high
• Accommodates copper and fiber optic
modems
• Indicator LEDs on each card
• V.54 diagnostics available with several
cards
• Redundant power supply
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The CMN-16 compact modem nest is a space-saving
rack that houses up to 16 short range modem cards.
Most of the cards carry two modems, doubling the
capacity of the nest to up to 32 modems. The nest
provides an inexpensive solution to central site racking
of short range modems. In addition to short range
modems, the nest supports interface converters, fiber
optic modems and elastic buffers.
The CMN-16 is compatible with the SRM short range
modem family and has the added capability of
displaying activity on the interface signals.
The following cards are available:
CMN-C6A – dual async short range modem
card, compatible with SRM-5A, SRM-6A,
SRM-3A
CMN-C6AC – dual async multipoint short
range modem card, compatible with
SRM-5AC, SRM-6AC
CMN-C6S – sync short range modem card,
compatible with SRM-5S, SRM-6S
CMN-C6SC – sync multipoint short range
modem card, compatible with SRM-5SC,
SRM-6SC
CMN-C6TX – dual async 2 -wire short range
modem card, compatible with SRM-5TX
CMN-C8 – sync/async short range modem
card with V.54 loops, compatible with
SRM-8, ASM-10/8
CMN-C8H – sync/async high speed short
range modem card with V.54 loops,
compatible with SRM-8H
CMN-CF6A – dual async fiber optic short
range modem card, compatible with
FOM-5A, FOM-6A
CMN-CF8 – sync/async fiber optic modem
card with V.54 loops, compatible with
FOM- 8
CMN-C11 – async short range modem card
with V.54 loops, compatible with ASM-11,
and with ASM-10/8 and SRM-8 in async
mode
CMN-CEB – elastic buffer for connecting
two independently clocked DCEs
CMN-C423/422 – interface converter from
RS-423/V.10 to RS-422/V.11
Several plug-in power supplies are available
for 115/230 VAC and –48 VDC operation.
The card nest can be supplied with two
totally independent plug-in power supply
units, providing redundancy and automatic
backup. A standalone 115/230 VAC high
power version supports two card nests via
cable and card connection.
The CMN-16 is available as a 19" rack
mount enclosure and is 2U (3.5") high.
RAD Data Communications 2006 Catalog
147
Page 3
MINIATURE SHORT RANGE MODEMS
SRM-31S
128 kbps
2-wire
8km
(5 miles)
LRS-24
ASMi-31-2C
Digital
Network
DTE
SRM-8H SRM-8H
IBM 37X5
56/64 kbps
4-wire
IBM 3174
SRM-31S
Miniature Multirate 2-Wire Modem
• Full duplex transmission over 2 wires in
synchronous transmission
• Data rates up to 128 kbps
• Transmission range up to 8 km (5 miles),
independent of data rate
• Supports IDSL technology (ISDN, U
interface)
• Works opposite the ASMi-31 modem,
including remote control and monitoring,
and LRS-24 modem rack (ASMi-31-2C)
Visit www.rad.com for latest product updates
The SRM-31S miniature synchronous
modem operates full duplex over a single
pair of wires. It supports data rates from
1.2 kbps to 128 kbps. The transmission
range is up to 8 km (5 miles) over 24 AWG
cable, independent of the data rate.
IDSL technology (ISDN, U interface) provides
extended range and efficient transmission
over a single copper pair.
The SRM-31 can operate opposite the
ASMi-31 modem, supporting remote control
and monitoring. When the ASMi-31 is a card
in the LRS-24 rack, the SNMP central
management station can perform control
and monitoring of the remote SRM-31.
Power is provided by a wall-mounted power
supply that is supplied with the product.
End-to-end signaling is available with no
interference to data transmission. The user
can select between RTS/DCD and DSR/DTR
end-to-end signaling options.
SRM-8H
High Speed Short Range Modem
148
• Selectable sync or async operation
• V.54 local and remote diagnostics
• Full or half duplex operation over 4 wires
• Selectable data rates: 56 or 64 kbps
• Range up to 4.5 km (2.8 miles) for 24 AWG
• Controlled or continuous carrier
• Four interfaces: RS-232/V.24, V.35, X.21, RS-530
• Four LED indicators
• Powered via wall-mount power supply
• Line connector options: terminal block,
RJ-12 and RJ-45
Visit www.rad.com for latest product updates
RAD Data Communications 2006 Catalog
The SRM-8H is a high speed short range
modem operating full duplex over twisted
pair, unconditioned telephone lines. It has
an extended range of 4.5 km (2.8 miles) for
24 AWG at data rates of 56 or 64 kbps.
The SRM-8H has diagnostic capabilities
complying with ITU V.54 standard. Two loops
are available: local analog loop and remote
digital loop.
The modem’s carrier can be strapped for
either continuous or switched operation,
controlled by the RTS signal, for passing
control signals.
Transmit timing can be selected for internal,
external or loopback clock. Four LED
indicators monitor Transmit Data, Carrier
Detect, Test and Power.
Four interface models are available:
RS-232/V.24, V.35, X.21, and RS-530.
Power is provided by a standard wallmounted power supply. Connection of
modems to the line is usually via a 5-screw
terminal block. Other connectors available
are RJ-12 and RJ-45.
The modem is also available as a card
version for mounting in a 19" rack (see the
CMN-16 nest, card CMN-C8H).
Approximate Range (at 56/64 kbps)
Gauge 19 AWG 24 AWG 26 AWG
(0.9 mm) (0.5 mm) (0.4 mm)
Range 10 km 4.5 km 3.2 km
(6.0 miles) (2.8 miles) (2.0 miles)
Page 4
SRM-6AC SRM-5AC
SRM-5AC
SRM-5AC
Async
computer
Async
terminal
TXRXRX
TX
RX
TX
RX
TX
• SRM-5A/6A: 4-wire, full duplex
SRM-6A
Async
computer
4-wire
Async
terminal
SRM-5A
SRM-6L: 4-wire, full or half duplex
• Internal filter for high noise immunity
(SRM-5A)
• Insensitive to wire polarity (SRM-6L)
• Data rates up to 19.2 kbps
• DCE/DTE switch
• No external power required
• Transformer line isolation
• Available as a card for 19” rack (SRM-6A)
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The miniature SRM-5A, SRM-6A and SRM-6L are
asynchronous short range modems connecting full
duplex asynchronous terminals to computers. The
SRM-5A and SRM-6A operate at data rates of up to
MINIATURE SHORT RANGE MODEMS
SRM-5A, SRM-6A, SRM-6L
Asynchronous Short Range Modems
19.2 kbps with a range of 4.5 km (2.8 miles)
at 9.6 kbps. The SRM-6L operates at data
rates of up to 19.2 kbps up to a range of
3.2 km (2 miles).
The SRM-5A is fully compatible with the
SRM-6A and offers the same features in
half the size.
The SRM-6L offers the unique feature of
insensitivity to wire polarity: There is no
need to observe + and – connections when
using twisted pairs, making it easy to install
and maintain.
The DCE/DTE switch allows operation as a
DTE for connection to another DCE, without
requiring a cross cable. All three units
operate without external power by drawing
low power from the data and control signals.
Connection to the line is through isolation
transformers for protection against AC or DC
overvoltages.
The SRM-5A modem is available with an
internal filter (optional for the SRM-6A). The
filter is designed to overcome radiated and
conducted interference for high noise
immunity.
The SRM-6A is also available as a card for
mounting in a 19" rack (see the CMN-16
nest, card CMN-6A).
Approximate Range (for 24 AWG/0.5 mm)
Data Rate
kbps km miles
19.2 2.0 1.2
9.6 4.5 2.8
4.8 5.0 3.0
1.2–2.4 5.5 3.4
12
MINIATURE SHORT RANGE MODEMS
• 4-wire, full or half duplex
• Controlled carrier for multipoint
• Transfers one control signal
• Data rates up to 19.2 kbps
• Range up to 3.5 km (2.2 miles)
• DCE/DTE switch
• LED indicator for carrier detect (SRM-5AC only)
• No external power required
• Line connector options: terminal block,
• Available as a card for 19” rack
Visit www.rad.com for latest product updates
RJ-12 and RJ-45
SRM-5AC, SRM-6AC
Asynchronous Multipoint Short Range Modems
The miniature SRM-5AC and SRM-6AC are
short range modems connecting full or half
duplex asynchronous terminals to
computers. Featuring carrier control, the
modems can be used in multipoint
applications and where end-to-end transfer
of a control signal is required. They operate
at data rates up to 19.2 kbps with a range
of up to 3.5 km (2.2 miles) over 24 AWG.
The SRM-5AC is a compatible sub-miniature
model of the SRM-6AC, offering the same
features in half the size.
The carrier can be strapped to be constantly
ON, or controlled by the Request to Send
signal. A switch-selectable DTE/DCE option
allows the modems to operate as a DTE for
connection to another DCE, without
requiring a cross cable.
The modems are available with an internal
filter (optional for the SRM-6AC). The filter
is designed to overcome radiated and
conducted interference for high noise
immunity.
Connection to the line is usually via a
5-screw (4-wire and ground) terminal block.
Optional connectors available for the
SRM-6AC are RJ-12 and RJ-45. The SRM-5AC
has both terminal block and RJ-12 or RJ-45
as its line connectors.
The modems are also available as a card for
mounting in a 19" rack (see the CMN-16
nest, card CMN-C6AC).
RAD Data Communications 2006 Catalog
149
Page 5
MINIATURE SHORT RANGE MODEMS
4-wire
SRM-5S SRM-5S
Sync
computer
Sync
terminal
SRM-6SC SRM-5SC
SRM-5SC
SRM-5SC
Sync
computer
Sync
terminal
TXRXTX
RX
TX
RX
TX
RX
SRM-5S
Synchronous Short Range Modem
• 4-wire, full duplex
• Selectable data rates up to 19.2 kbps
• Range up to 5 km (3.0 miles) at 9.6 kbps
• Full or half duplex, point-to-point
• LED indicator for carrier detect
• No external power required
• Line connector options: terminal block,
RJ-12 and RJ-45
Visit www.rad.com for latest product updates
The miniature SRM-5S is a short range
modem connecting full duplex synchronous
terminals, controllers and computers. It
operates at nine data rates up to 19.2 kbps.
When operating at 9.6 kbps, the modem
supports ranges up to 5 km (3.0 miles).
The modem operates without external
power, by drawing low power from the data
and control signals.
Connection to the line is through isolation
transformers for protection against AC or DC
overvoltages. Transmit timing is provided by
an internal clock.
The unit has an RS-232/V.24 interface and is
available with an integral male or female
25-pin connector for the DTE interface and
a 5-screw (4-wire and ground) terminal
block for the line.
The SRM-5S has both a terminal block and
an RJ-45 or RJ-12 line connector.
The modem is also available as a card for
mounting in a 19" rack.
Approximate Range (for 24 AWG/0.5 mm)
Data Rate
kbps km miles
19.2 4.0 2.5
9.6 5.0 3.0
4.8 5.5 3.4
2.4 5.5 3.4
1.2 6.0 3.7
SRM-5SC, SRM-6SC
Sync Multipoint Short Range Modems
• 4-wire, full or half duplex
• Selectable data rates: 1.2 to 19.2 kbps
• Range up to 5 km (3 miles) at 9.6 kbps
• Transfers one control signal
• Internal, external or loopback clock
• No external power required
• LED indicator for carrier detect (SRM-5SC only)
• Line connector options: terminal block, RJ-12
and RJ-45
Visit www.rad.com for latest product updates
The miniature SRM-5SC and SRM-6SC are short range
modems connecting full or half duplex synchronous
terminals, controllers and computers in point-to-point or
150
point-to-multipoint applications. The modems operate at
data rates from 1.2 kbps to 19.2 kbps (selectable) with
a range of 5 km (3.0 miles) at 9.6 kbps.
RAD Data Communications 2006 Catalog
The SRM-5SC is a fully compatible subminiature model of the SRM-6SC, offering
the same features in half the size.
Three alternative sources for transmit timing
are available: internal oscillator, external
clock from the terminal or loopback clock
derived from the receive signal. The carrier
can be strapped for continuous operation or
switched operation controlled by the RTS
signal.
The units have an RS-232-C/V.24 interface,
and are available with a choice of a male or
female integral 25-pin connector for the DTE
interface and a 5-screw (4-wire and ground)
terminal block for the line. Optional line
connectors available for the SRM-6SC are
RJ-12 and RJ-45. The SRM-5SC has both a
terminal block and RJ-45 or RJ-12 as its line
connectors. The modem is also available as
a card version for mounting in a 19” rack
(see the CMN-16 nest, card CMN-C6SC).
Approximate Range (for 24 AWG/0.5 mm)
Data Rate
kbps km miles
19.2 4.5 2.8
9.6 5.0 3.0
4.8 6.0 3.7
1.2 – 2.4 6.5 4.0
Page 6
MINIATURE SHORT RANGE MODEMS/
FOM-485
RS-485
4-wire
Main
controller
Fiber
RTU
FOM-485
Mainframe
Laptop
computer
4-wire
SRM-3A SRM-3A
MINIATURE FIBER 0PTIC MODEMS
SRM-3A
Ultra-Miniature Async Short Range Modem
12
MINIATURE SHORT RANGE MODEMS / MINIATURE FIBER 0PTIC MODEMS
• RS-232/V.24 on 9-pin connector
• 4-wire, full duplex
• Data rates up to 19.2 kbps
• Transformer-isolated
• No external power required
• Compatible with the SRM-5A and SRM-6A
Visit www.rad.com for latest product updates
The SRM-3A is an ultra-miniature
asynchronous short range modem connecting
full duplex asynchronous terminals to
computers. Using 24 AWG and operating at
9.6 kbps, it has an extended range of
4.5 km/2.8 miles. It typically operates at data
rates up to 19.2 kbps.
The combination of the modem’s miniature
size and the use of a 9-pin D-type
connector makes it particularly suitable for
PCs, for connecting laptop computers to a
mainframe and for UNIX systems such as
Unisys U6000/50.
The SRM-3A is coupled to the line through
isolation transformers for protection against
AC or DC overvoltages. SRM-3A operates
without external power by drawing low
power from the DTE data and control
signals. The modem will operate fully even if
only Transmit Data is connected, i.e.,
without any control signals.
The modem connects to the DTE via a 9-pin
connector, male or female. Connection to
the line is via a 4-screw terminal block,
RJ-11 jack or RJ-45 jack.
Approximate Range (for 24 AWG/0.5 mm)
Data Rate
kbps km miles
19.2 1.0 0.6
9.6 4.5 2.8
4.8 6.0 3.7
2.4 7.0 4.3
1.2 7.0 4.3
FOM-485
Miniature RS-485 Fiber Optic Modem
• Converts from RS-485 to fiber
• Asynchronous transmission up to 115.2 kbps
• Transmission range up to 40 km (25 miles)
over single mode fiber
• Full duplex over 4-wire or half duplex over
2-wire
• V.54 diagnostics
• LED indicators for status display
Visit www.rad.com for latest product updates
The FOM-485 is an asynchronous miniature
fiber optic modem that transmits RS-485
signals over fiber optic cables. The FOM-485
is used in utility applications where there is
a need to connect the main controller to a
remote terminal unit (RTU).
The FOM-485 allows connection of up to
32 RTUs to a single host, at a wide range of
data rates up to 115.2 kbps, at typical
distances up to 40 km (25 miles) over
single mode fiber.
The FOM-485 supports full duplex
transmission over 4-wire or half duplex over
2-wire cables. It supports diagnostic
capabilities complying with the ITU V.54
standard.
The modem has six LED indicators to display
the status of the modem: TD, RD, DCD, RTS,
TEST, and ERR.
RAD Data Communications 2006 Catalog
151
Page 7
MINIATURE FIBER OPTIC MODEMS
FOM-9 FOM-9
128 kbps 128 kbps
Fiber optic
cable
15 km
(9 miles)
FOM-8H FOM-8H
IBM 37X5
56 or 64 kbps
Fiber optic cable
IBM 3174
FOM-9
Sync/Async High Speed Fiber Optic Modem
• Selectable sync or async operation
• Selectable data rates from 9.6 kbps to
128 kbps
• Range up to 15 km (9 miles) over single
mode fiber
• Built-in BER tester and V.54 diagnostic loop
support
• Carrier control mode for end-to-end signaling
• LED indicators for status display
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The FOM-9 is a miniature sync/async fiber
optic modem operating full or half duplex
over fiber optic cable. It has a range of
15 km (9 miles) over single mode fiber and
operates at selectable data rates up to
128 kbps.
The FOM-9 includes a built-in BER tester
that generates a 511-bit pattern and can be
used for testing the link integrity. Diagnostic
loopbacks according to ITU V.54 can be
activated for fault isolation. Two types of
diagnostic loops are supported: local analog
loop and remote digital loop. The loopback
options and the BER tester can be activated
by toggling pin 18 or 21 on the V.24/RS-232
interface.
When set to asynchronous mode, the
modem internally converts the transmission
to synchronous format, in compliance with
the ITU V.14 standard.
The FOM-9 includes innovative circuits that
allow operation without external power, by
drawing low power from the DTE data and
control signals. In cases where the DTE
cannot provide enough power, the FOM-9
includes a special jack that can be connected
to an external AC power supply adapter.
The modem has six LED indicators to display
the status of the modem: TD, RD, DCD, RTS,
TEST, and ERR.
FOM-8H
High Speed Fiber Optic Modem
152
• Sync or async transmission at 56 kbps or
64 kbps
• V.54 diagnostics
• Range up to 4 km (2.5 miles) over
multimode fiber
• Controlled or continuous carrier
• V.24/RS-232, V.35, RS-530, or X.21 interface
Visit www.rad.com for latest product updates
RAD Data Communications 2006 Catalog
The FOM-8H is a high speed fiber optic
modem operating full or half duplex over fiber
optic cable. It has a range of 4 km (2.5 miles)
at data rates up to 56 kbps or 64 kbps.
The FOM-8H has diagnostic capabilities
complying with the ITU V.54 standard. Two
loops are available: local analog loop and
remote digital loop. These are activated by
a manual switch or by toggling the
corresponding pins of the DTE interface (not
applicable with X.21 interface).
Transmit timing is provided by one of three
alternative sources:
• internal oscillator
• loopback clock derived from the receive
signal
• external clock from the terminal
The carrier can be strapped for either
continuous or switched operation,
controlled by the RTS signal.
Several interface options are available:
RS-232/V.24, RS-530, X.21, or V.35. The
modem has LED indicators for TD, DCD,
TEST, and POWER. The FOM-8H is packaged
in a lightweight plastic case.
Page 8
FOM-8 FOM-8
Fiber optic cable
• Selectable sync or async operation
RS-232
Host
Fiber optic
Remote terminal units
FOM-6MP/SL
FOM-6MP/DL FOM-6MP/DL FOM-6MP/DL
• V.54 diagnostics
• Selectable data rates up to 19.2 kbps
• Two versions: single mode and multimode
• Range up to 15 km (9 miles) over single
mode fiber
• Carrier-controlled for transfer of control signal
• No external power required
• Metal case
• Card version
Visit www.rad.com for latest product updates
The FOM-8 is a sync/async fiber optic modem
operating full or half duplex over fiber optic cable. It
has a range of 15 km (9 miles) over single mode fiber
and operates at selectable data rates up to 19.2 kbps.
MINIATURE FIBER OPTIC MODEMS
FOM-8
Sync/Async Fiber Optic Modem
The FOM-8 has diagnostic capabilities
complying with the ITU V.54 standard.
Two loops are available: local analog loop
and remote digital loop. These are activated
by toggling pin 18 or 21 of the V.24/RS-232
interface.
In synchronous transmission, the transmit
timing can be selected for internal, external
or loopback clock. Asynchronous
transmission is converted internally to sync
format in compliance with the V.14
standard. Different async formats are
switch-selectable.
Innovative circuitry design allows operation
without external power, by drawing low
power from the DTE data and control
signals. The FOM-8 is packaged in a metal
case for reduction of EMI/RFI emissions.
The modem is available as a card for
mounting in a 19" rack (see CMN-16 nest,
card CMN-CF8).
12
MINIATURE FIBER OPTIC MODEMS
• Asynchronous transmission up to 38.4 kbps
• Multidrop operation over a fiber link
• Transmission range up to 46 km (28 miles)
over single mode fiber
• RTS or data contention for multipoint
operation
• Automatic disabling in the event of streaming
• Variety of optical options, including:
multimode, single mode and laser diode
for extended range
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The FOM-6MP async fiber optic modem operates over
fiber to connect remote terminals and computers,
connected in multidrop, to a central host. Transmission
range (regardless of the data rate):
• 3.5 km (2 miles) using 850 nm multimode fiber
FOM-6MP
Async Fiber Optic Multipoint Modem
• 30 km (18 miles) using 1310 nm single
mode fiber
• 46 km (28 miles) using 1310 nm laser
diode single mode fiber
The FOM-6MP contains two optical
interfaces and one V.24/RS-232 port. One
optical interface passes data to and from
the host while the other passes data to and
from the rest of the terminals in the chain.
The V.24/RS-232 interface is connected to
the local terminal.
Terminal contention for transmission to the
host is selectable: transmitting data or
raising RTS signal.
The FOM-6MP includes anti-streaming
protection which prevents blockage of data
transmission. The FOM-6MP disables a port
that blocks the polling for a preset, userselectable period of time.
LED indicators help the user to easily isolate
faulty segments along the chain of terminals.
The FOM-6MP requires an external DC
power supply of 10–30 VDC/500 mA.
RAD Data Communications 2006 Catalog
153
Page 9
FOM-6AV FOM-6AV
Fiber optic cable
Host
Async
terminal
• Asynchronous transmission up to 57.6 kbps
FOM-6A
Async
computer
Async
terminal
FOM-5A
Fiber optic cable
• Supports any type of asynchronous
characters with no need for configuration
• Transmission range up to 16 km (10 miles)
over single mode fiber
• Full or half duplex
• Continuous or controlled carrier
• DTE/DCE switch
• No external power required
Visit www.rad.com for latest product updates
The miniature FOM-6AV high speed fiber optic modem
is used for transmission of asynchronous data over
fiber optic links. It operates at any data rate up to
57.6 kbps and supports any type of asynchronous
characters with no need for configuration.
MINIATURE FIBER OPTIC MODEMS
FOM-6AV
High Speed Fiber Optic Modem
Transmission over fiber ensures data
integrity, high immunity against EMI/RFI and
data security. The modem supports ranges
of up to 3 km (1.9 miles) over multimode
fiber and up to 16 km (10 miles) over single
mode fiber.
End-to-end signaling is available using the
carrier between the modems in controlled
carrier mode. When RTS is raised on one
end, it causes the DCD to rise on the other
end of the link.
Innovative circuitry allows the modems to
operate without external power, by drawing
low power from the DTE data and control
signals.
The FOM-6AV has a V.24/RS-232 interface
and is available with either a male or female
integral D-type 25-pin connector.
The product includes an LED for indicating
data transmission over the link.
The modem is available in a metal casing
(ordering option) to increase data
transmission security and EMI/RFI immunity.
• Asynchronous transmission up to 19.2 kbps
• Transmission range up to 3 km (1.9 miles)
over multimode fiber
• Full or half duplex
• Continuous or controlled carrier
• DCE/DTE switch
• LED indicator for data transmit
• No external power required
• Optional metal case (FOM-6A only)
• Available as a card for 19" rack
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154
RAD Data Communications 2006 Catalog
FOM-5A, FOM-6A
Asynchronous Fiber Optic Modems
FOM-5A and FOM-6A are miniature fiber
optic modems used for local data
distribution, connecting full or half duplex
async computers and terminals. A pair of
modems ensures integrity of data
transmission over multimode fiber optic
cables for distances up to 3 km (1.9 miles)
at data rates up to 19.2 kbps.
The FOM-5A is a sub-miniature version of
the FOM-6A, offering all the features in half
the size.
Innovative circuitry allows the modems to
operate without external power, by drawing
low power from the DTE data and control
signals.
The FOM-5A and FOM-6A have a V.24/RS-232
interface and are available with either a male
or female integral 25-pin connector.
The modem is available as a card for
mounting in a 19" rack (see the CMN-16
nest, card CMN-CF6A).
Page 10
MODEM ELIMINATORS
100 m
330 ft
100 m
330 ft
IBM 37X5 IBM 3174
MME up to 19.2 kbps
MME/V.35 56/64 kbps
MME, MME/V.35
Replaces Two Sync Modems
12
MINIATURE FIBER OPTIC MODEMS / MODEM ELIMINATORS
• Data rates
MME: selectable up to 19.2 kbps
MME/V.35: 56/64 kbps
• Interfaces
MME: RS-232/V.24
MME/V.35: V.35
• Range of 100m (330 ft) on each side
• Selectable RTS-to-CTS delay
• Carrier-controlled or constantly ON
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The MME and MME/V.35 miniature modem eliminators
replace two synchronous modems, permitting direct
DTE-to-DTE connection. They have a maximum range
of 100 m (330 ft) on each side. MME
operates at selectable data rates up to 19.2
kbps. MME/V.35 operates at 56/64 kbps,
replacing high speed modems.
The MME and MME/V.35 generate the
receive and transmit clocks internally for the
two synchronous DTEs as well as the control
signals necessary to emulate half or full
duplex operation.
The delay between Request to Send and
Clear to Send can be independently set (on
the MME, on port 0 or 6.6, or 53 msec; and
on the MME/V.35, on port 0 or 7, or
64 msec). Carrier Detect signal can be set
to constantly ON, or used as a DTE-to-DTE
handshaking signal where RTS on one port
is converted to DCD on the other port.
Three models are available:
• MME requires no external power supply,
drawing low power from the data and
control signals. Physical connection
between the MME and the DTEs is via
25-pin D-type connectors, either male
or female.
• MME/V.35 requires no external power
supply, drawing low power from the V.35
control signals.
• MME/V.35P has a jack for connection to
an external wall-mounted power supply of
9.12 VDC/200 mA. The MME/V.35P is used
in applications where the DTEs do not
provide the control signals necessary to
power the MME/V.35.
Physical connection between the MME/V.35
and the DTEs is via two 34-pin V.35
connectors, each on a 30 cm (1 ft) cable.
RAD Data Communications 2006 Catalog
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