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Cisco CGS 2520 Hardware Installation Guide
OL-31444-01
Chapter 1 Product Overview
Ports
You can order this cable (part number CAB-SFP-50CM=).
Power-Input Terminal
The power-input terminal provides screw terminals for the AC and DC power connections. The switch
can operate with one or two power supplies. If one of the power sources fail, the other continues to power
the switch. For more information, see the “Power Supply Installation” section on page 3-1.
Figure 1-4 Power-Input Terminal
Alarm Ports
The switch has four alarm inputs and one alarm output. The alarm setting is open or closed.
• Open means that the normal condition has current flowing through the contact (referred to as a
normally closed contact). The alarm is generated when the current stops.
• Closed means that no current flows through the contact (referred to as a normally open contact). The
alarm is generated when the current flows.
This section contains the following alarm port information:
• Alarm Input, page 1-7
• Alarm Output, page 1-7

Alarm Input

The alarm input is a dry-contact alarm port. You can connect up to four alarm inputs from devices, such
as a door, a temperature gauge, or a fire alarm, to the alarm port. You can use the CLI to set the alarm
severity to minor, major, or critical. An alarm generates a system message and turns on an LED. See the
“Alarm LEDs” section on page 1-10 for the LED descriptions.

Alarm Output

The alarm output can be configured as a minor or major alarm. Output alarms often control an external
alarm, such as a bell or a light. To connect an external alarm device to the relay, connect two relay contact
wires to complete the electrical circuit. See the “Alarm Port” section on page B-3 for information on the
alarm pinouts.
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