DPX16: Instructions for Basic Operation and Installation
Page 24
A
LARM
I
NTERCONNECTION ON THE
DPX16
Each alarm connector on the back panel allows input of eight
external control signals to affect the behavior of the
multiplexer under alarm conditions. Alarm inputs are
provided for each camera. A picture “Freeze” input is also
provided to allow the picture to be frozen. These inputs are
normally generated by a switch located at a door, window or
other point in the installation where a camera is monitoring
activity. Many installations use a “normally open” switch
which requires a switch “closure” to activate the alarm. As
part of the DPX16’s normal alarm video processing, an
“alarm output” is generated on the same back panel
connector. In addition to the alarm inputs, a picture “Freeze”
input is also provided. While picture “Freeze” is activated,
any present camera image is retained on the display and
new video information is ignored. A picture freeze does not
trigger the alarm output.
Camera inputs contain series resistors for ESD (Electro
Static Discharge) and lightning damage protection, and the
outputs also contain series resistors to limit output current to
prevent damage to the DPX16 in the occurrence of “shorting
out” the output pin. When connecting the inputs and outputs
to other equipment, consideration should be given to the
limitations introduced by these current limiting
resistors.
The alarm connectors on the DPX16 are DB-15,
15 pin connectors. For ease of installation, a
“breakout” adapter is provided with the 16th terminal
connected to chassis ground. A simple alarm
connection is shown to the right using the DPX16
“alarm breakout” adapter. In this example, switches
are connected directly to the alarm inputs, and a
single output is connected to some signaling device
or to a controlled piece of equipment. In this case,
an external resistor is required to pull the output up
to +5V (High) indicating a non-alarm condition.
The external resistor makes connection to higher
voltage systems possible, such as a 12 Vdc
automobile system. In this application, the pull-up
resistor is not tied to the DPX16 +5V pin, but to the
higher voltage system. Voltages greater than +5V
must not exceed 30 Vdc and the current through the
output pin must not exceed 50 mA.
Failure to remain within the 30 Vdc and 50 mA
restriction could damage either the DPX16, the
output signaling device, or both.
1: Alarm #1
2: Alarm #2
3: Alarm #3
8: Alarm #8
11 KOhm
100 Ohm
100 Ohm
+5V
10: Freeze/Master
Enable
13: Alarm out pwr
15: Alarm ground
9: Alarm output
DPX Alarm Port Internal Electrical
Equivalent
(50 mA maximum)
Typical Alarm Connections
using the Breakout Adapter
Alarm Switches
OPEN = no alarm
CLOSED = alarm activate
1KOhm
+Vsupply
(30Vdc, 50mA max)
Alarm Output
(To indicator, VCR, etc.)
+5V = High = no alarm
0V = Low = alarm activated
Alarm Output
Vout = High = no alarm
0V = Low = alarm activated
1
16
1
16
