Cutler-Hammer D320 PLC, User Manual

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D320 PLC User's Manual
Alarm Output of Power Supply
Alarm Output (Power Supply)
•
The alarm output on the power supply turns On when the PLC is in Error mode.
•
The alarm output terminal has two relay contacts. These contacts are the NO (Normally Open)
contact, and the NC (Normally Closed) contact. They are located on the terminal strip of the
power supply. These contacts are provided for use as either an external alarm indication for
system fault, or for wiring as part of the emergency stop circuit for the system. They provide a
PLC-independent method of indication that the system is in fault.
Watchdog Timer
•
The watchdog timer detects program errors or hardware errors. The timer is On when the scan
time exceeds a user-defined time limit of up to 3 seconds.
•
When the watchdog timer detects a fault, the Error LED is lit, and the alarm contact of the
power supply turns On.
L
Power Module
COM
NC
ALARM
NO
Alarm signal
of lamp