46 JUPITER CM-4400 Control Module Installation and Operating Manual
Section 2 — Hardware Installation
Alarms in a Single CM-4400 Installation
If the master alarm is asserted by the main CPU watchdog timer (and
assuming that the power supply is operating properly), the CM-4400 will
be rebooted automatically.
Alarms in a Redundant CM-4400 Installation
For additional protection, a redundant CM-4400 can be installed. The
redundant CM-4400 will monitor the master CM-4400.
If a master alarm condition is detected
in the master unit, control will be
switched to the redundant CM-4400 automatically. The switch over to the
redundant unit will occur almost immediately after the alarm, thus pro-
viding minimal disruption to the contr
ol system. The controlling CM-4400
is indicated by a green light on the CM’s
Activate button (see Figure 2 on
page 32).
If the redundant CM-4400 is controlling the system and enters an alarm
c
ondition and then reboots:
• The redundant CM-4400 will retain control if the master has not recov-
er
ed.
• The master CM-4400 will assume control if the master has recovered
from an earlier automatic reboot.
Manually Switching A CM-4400
To manually change the operation from the master CM-4400 to the redun-
dant CM, press the
Activate button on the front panel of the redundant CM.
To return operation to the master CM, press the
Activate button on the
master CM.
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