7705 SAR-8 Overview
7705 SAR-8 Installation Guide Page 51
Monitoring Temperature
The operation of the fans in the version 2 fan modules (introduced in Release 2.0) are
controlled by software and hardware based on the following temperature monitoring.
• The air temperature inside the 7705 SAR-8 is continually monitored by a hardware-
controlled temperature switch on the fan module. Fans turn ON when the
temperature at the switch exceeds 107°F (42°C) and OFF when the temperature
drops below 89°F (32°C). This temperature monitoring is present even in the
absence of the CSMs.
• During normal operation, the CSMs and adapter card temperatures are monitored by
temperature sensors on each card. Fans are forced ON if any of the sensors exceeds
131°F (55°C). Fans will remain forced on (regardless of what the hardware-
controlled temperature switch on the fan module indicates) until all the card
temperatures reach or drop below 50°F (10°C).
An overheat alarm is raised if any card sensor temperature reaches or exceeds 167°F
(75°C).
Card Temperatures
Each CSM and adapter card has temperature sensors to continuously monitor its own
temperature and report the temperature to the CSM. The CSM continuously monitors the
temperature reported from any card that is in the system abnormal temperature state.
• If the temperature of any adapter card exceeds 185ºF (85ºC), the card is rebooted by
software. When the card comes up, it will display as being in the failed state, with
the reason “Card has overheated”. Once the temperature drops to 158°F (70°C) or
below, the card will go into the “booting” state and complete its reboot cycle.
• If the temperature of any card exceeds 243°F (117°C), the card is shut down until
the temperature drops to an operationally safe temperature. At that point, the card
will automatically reboot and be brought back into service.
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