Omega Products LDM70-P User Manual

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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.

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LDM70 Series Fully Isolated Limited Distance Modem

12VAC

AC GND

6' min.

(1.8)

12VAC

AC GND

Wall Transformer

(included with

PT, ST, PJT, SJT models)

Up to 12 miles

(20 km)

Dimensions Shown in Inches (mm)

Extended Warranty

Program

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

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

(

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

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)

VAC

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.

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AVAILABLE FOR FAST DELIVERY!

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