P
P
E
E
S
S
1
1
9
9
0
0
0
0
G
G
i
i
G
G
S
S
M
M
R
R
e
e
p
p
e
e
a
a
t
t
e
e
r
r
— Chapter 7. Connecting External Alarms
PES1900NR Operations Manual
104
Digital User-Controlled Outputs
The repeater includes two digital outputs, each with one lead for an open-transistor collector. When
the RepeaterNet software sets one of these digital output switches to ON, the repeater sends a drive
voltage to the input resistor of the transistor pair, as shown in Figure 85.
This drive voltage causes the transistor to saturate. Because the transistors are configured in a
Darlington pair, the on-state saturation voltage is about 1 volt. This makes these outputs unsuitable
for driving TTL loads directly. However, these two outputs can drive any other type of DC load, within
their maximum ratings. Outputs are
not
isolated from the repeater’s power subsystem, and the
repeater’s chassis ground terminal is the ground reference point for all inputs and outputs. Each of
the digital outputs has the following maximum characteristics.
Forward Current (I
C
)
continuous
500
mA
Maximum collector-to-emitter voltage (V
CE
)
50
Volts
Collector-to-emitter saturation voltage (V
CE(SAT)
)
1.0 Volt
Leakage Current in OFF State (maximum)
50 µA
Figure 91 depicts the equivalent circuitry of each user-controlled digital output.
Figure 85 User-Controlled Digital Output - Typical
Figure 86 shows two typical applications for digital outputs.
Refer to the
“Alarm Control Status Screen”
in Chapter 9,
Configuring the Repeater
, for
instructions about activating digital outputs.