User's Manual

Table Of Contents

22 LEDR Series I/O Guide MDS 05-3627A01, Rev. D

Input Connections In addition, four external alarm input lines (Pins 1, 2, 3 & 4) are pro-

vided. Normally, the input is either left open or shorted to ground, to

indicate an alarm condition.

Each alarm input is diode-clamped to +3.3 Vdc or chassis ground, and

can tolerate inputs from -4 to +6 Vdc without drawing excessive current.

If left open, each input is pulled up. To indicate an alarm condition, short

the input pin to the ground provided on the alarm connector (Pin 5). The

maximum DC loop resistance is 2 KΩ. These alarm input lines can tol-

erate circuit “bounce” common with mechanical relays.

NOTE: The normal (unalarmed) state of the contacts (open or closed)

or input alarm state (high or low) can be selected by a software

subcommand. See “alarm” on Page 50 for details.

Alarm Events The events that cause alarm output signals can be configured in the radio

software. See “evmap” on Page 58 for information on programming

which events trigger an alarm.

See Figure 38 on Page 129 for Alarm I/O pinout information.

DC Power Input (Primary Power)

The

DC POWER INPUT connector is a three-pin keyed connector used to

connect an external DC power source. A label next to the power con-

nector indicates the nominal voltage of the radio. Table 9 lists the actual

operating voltage ranges.

The connector matches with a power plug (MDS Part No. 73-1194A22)

which contains binding posts for attaching the positive and negative

power leads. The polarity of the power connections does not matter; the

positive and negative leads may be connected to either the left or right

binding posts as shown in Figure 11 and Figure 12. The center con-

ductor is not connected in the LEDR chassis and should be left unwired.

Before connecting primary power to the radio, verify that the source

provides a voltage within the proper operating range. Improper voltages

may damage the equipment. Permissible voltage limits are shown in

Table 9.

Table 9. Primary Power Input Options

Nominal Voltage Operating Range

24 Vdc 19.2 to 28.8 Vdc

48 Vdc 38.4 to 57.6 Vdc

CAUTION

POSSIBLE

EQUIPMENT

DAMAGE