Omega Products LDM70-P User Manual

$

205

Basic Unit

⻬ DC to 57,600 Baud
⻬ Complete Isolation

with Optical Couplers
and Power DC-to-DC
Converter

⻬ Data Terminal Ready,

Carrier Detect
Handshake Without
Extra Wires

⻬ Surge Protectors
⻬ Four LED Diagnostic

Indicators

⻬ Operation to 3 Miles

(5 KM) at 9600 Baud,
1 Mile (1.7 KM) at 19,200,

0.5 Miles (0.8 KM) at
57,600

⻬ Four-Wire Full Duplex,

Two-Wire Simplex

⻬ Self-Powered or

Host-Powered

⻬ Selection of Connectors
⻬ Wide Operating

Temperature Range:
0 to 70°C

The LDM70 Series of products is
designed to allow video display
terminals (VDTs) and other RS-232
devi ces to be connected over
distances sufficient to cover any
industrial or institutional complex of
build ings. These modems feature a
rugged aluminum en clo sure small
enough to mount on the back panel
of VDT units, saving valuable desk
and floor space.

The LDM70 Series is designed for
full duplex, asyn chro nous operation
over two DC-continuity, non-load ed,
twisted-wire pairs. Through special
high-speed op ti cal ly coupled
circuits, they may com mu ni cate at
data rates up to 57,600 baud.

A handshake operation is
implemented over the same
two-wire pairs. A self-powered
model and a host-powered model
are avail able. The self-powered unit
uses 12 Vac from a wall-mounted
trans form er, while the host-powered
unit takes ±DC power from pins
9 and 10 of the RS-232 connector.
The modem circuits—and,
consequently, the host device—are
protected from electrical tran sients
due to lightning strikes or operation
of heavy in dus tri al equipment.

Each de vice features a convenient
Data-Communication Equipment
(DCE) to Data-Terminal Equipment
(DTE) switch which reverses pins
2 and 3 of the RS-232 connector.

J-11

LDM70 Series Fully Isolated Limited Distance Modem

12VAC

AC GND

+

-

+

-

+

-

+

-

6' min.

(1.8)

RD

TD

12VAC

AC GND

RD

TD

Wall Transformer

(included with

PT, ST, PJT,
SJT models)

Up to 12 miles

(20 km)

Dimensions Shown in Inches (mm)

Extended Warranty

Program

SM

Includes operator’s manual. Transformer powered units also include 120 Vac wall mount transformer.

OMEGACARESMextended warranty is available for models shown on this page.
Ask your sales representative for full details when placing order.

Ordering Example: LDM70-ST converter,

OMEGACARE

SM

1 year warranty for LDM70-ST

(adds 1 year to standard 1 year warranty) $226 + 25 = $251.

Model LDM70

Baud Rate Range 0 – 57.6K
Baud Rate 57.6K 38.4K 19.2K 9.6K 4.8K 2.4K 1.2K – 0

Distance (miles) 0.5 0.75 1.0 3 5 8 12

Distance (km) 0.8 1.25 1.7 5 8.3 13.3 20
Common Mode Isolation 1500V Surge, 1000 Vrms Continuous
Differential Mode

Surge Protection
(3 devices) ANSI/IEEE C37.90.1-1989

Channel Lines

(1)

TD, RD

Control Lines

(1)

DTR, RLSD

Modes Asynchronous 4-wire duplex, 2-wire simplex
Power:

AC operation

(

2)

12VAC at 120mA

DC operation ±9VDC to ±15VDC, 45mA
Operating Environment 0 to 70°C, 0 to 95% relative humidity, noncondensing
Dimensions 5.7 x 2.1 x 1" (144.8 x 53.3 x 25.4 mm)
Weight 156 g (5.5 oz) max

AC Transformer 311.8 g (11.0 oz) max

MTBF

(3)

>100,000 hrs

To Order

(Specify Model Number)

Model RS232 Field Power
Number Price Connector Connector Source

LDM70-P $205 25 Pin male Screw termination Host-powered
LDM70-S 205 25 Pin female Screw termination Host-powered
LDM70-PT 226 25 Pin male Screw termination Transformer
LDM70-ST 226 25 Pin female Screw termination Transformer

J

RD+ 2

RD- 3

TD+ 4

TD- 5

Modular Phone

Jack Option

Field Connector

RS-232 Connector

Connector C/L

1.852 (47.0)

2.1 (53.3)

Screw Terms

1.65 (41.9)

12

VAC

AC

GND
RD+

RD­TD+
TD-

1
2

000.315
(8.0)

0.531
(13.5)

0.120 (3.0) Dia

5.35

(135.9)

1.0 (25.4)

0.13 ±0.01 (3.3 ±0.25)

0.25 (6.4)

0.50 ±0.01 C/L
(12.7 ±0.25)

0.175 ±0.01
(4.4 ±0.25)

0.19 ±0.01
(4.8 ±0.25)

Dimensions: Inches (mm)

C/L = Center Line

Connector

Flange Detail

0.72

(18.3)

3
4
5
6

Notes: (1) TD = Transmit Data, RD = Receive Data, DTR = Data Terminal Ready, RLSD =
Received Line Signal Detect. (2) 120 Vac and 220 Vac power transformers are available. (3)
Ground-benign environmental conditions (no salt atmosphere, <50°C ambient temperature).

Specifications

For installation and trouble shooting,
each unit has di ag nos tic
Light-Emitting Diodes (LEDs) on the
transmit and receive lines. In
addition, LEDs indicate valid carrier
detect and data terminal ready.

The RS-232 connector may be
ordered as a male or female 25-pin
connector. Field connection is made
through a modern, solderless,
screw-termination as sem bly.
Alternatively, a con ve nient four-wire
mod u lar phone jack is available.

Interface

LDM70 conforms to EIA RS-232
and CCITT V.24 spec i fi ca tions.
Pins 4 and 5 are internally
connected. Pin 6, Data Set Ready
(DSR), is internally tied to the valid
state through a resistor. Data
Terminal Ready (DTR), pin 20, must
be asserted by the host equipment
before LDM70 can transmit data.
When DTR is asserted, the LDM70
at the other end of the com mu ni ­cations cable will assert Receive
Line Signal Detect (RLSD), pin 8, to
its host equipment. This is used by
host equipment to coordinate data
ex chang es. If a DTR signal is not
available from the host equipment,
an open circuit on pin 20 will be
equivalent to assertion, allowing
operation without hand shake. Pin 7
is signal ground. Pins 2 and 3 are
switch-reversible.

Isolation

The LDM70 is unique compared to
other popular limited-distance
modems in that it completely
isolates the host equip ment from the
field wiring through the use of
optical couplers and a DC-to-DC
converter. Units that use only optical
couplers break ground loops but
circuit power is still taken from an
unisolated source, and/or host
circuit ground is still connected to
one field wire pair. Thus, even
though the ground loop between the
two pieces of host equipment has
been broken, induced transient
currents will still flow from the field
wiring through the ground circuits of
the host equipment. This can cause
faulty operation of the host
equipment, or even damage in
extreme cases. To prevent this, the
LDM70 models have a transformer­cou pled DC-to-DC converter which
pow ers the field circuits, with no
path for induced transients to flow
into host equipment. This isolation
barrier is rated to 1000 Vrms.
Continuous operation at high
voltages is not recommended for
safety reasons.

J-12

AVAILABLE FOR FAST DELIVERY!