The LDM70 Series of products is
designed to allow RS-232
devices to be connected over
distances sufficient to cover any
industrial or institutional complex of
The LDM70 Series is designed for
full duplex, asynchronous operation
over two DC-continuity, non-loaded,
twisted-wire pairs. Through special
high-speed optically coupled
circuits, they may communicate 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 available. The self-powered unit
uses 12 Vac from a wall-mounted
transformer, 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 transients
due to lightning strikes or operation
of heavy industrial equipment.
Each device features a convenient
(DCE) to Data-Terminal Equipment
(DTE) switch which reverses pins
2 and 3 of the RS-232 connector.
For installation and troubleshooting,
each unit has diagnostic
Light-Emitting Diodes (LEDs) on the transmit and receive lines. In
addition, LEDs indicate valid carrier
detect and data terminal ready.
The RS-232 connection is through a 25-pin D sockect. Field connection is made
through a modern, solderless,
† All amounts shown in EUR, GBP, or USD Note: Includes operator’s manual. Transformer powered units also include ac wall mount transformer.