Motorola 900 series - Environmental Monitoring

Environmental Monitoring
Environmental Monitoring
There is a temperature sensing circuit located on the I/0 distribution board to
monitor the temperature in the CPU Module. A maximum of three high
temperature sensing circuits can be monitored by the I/0 distribution board
from the VME Expansion Module. The sensor combines the capability of
sensing ambient temperature fluctuations as well as airflow changes through
the chassis. The environmental conditions are sensed with respect to how well
self-heating devices with the computer chassis are being cooled.
By placing this
sensor inside the VME Expansion Module and the SCSI Device
Expansion
Module, the sensor's output can be monitored for proper cooling
within the chassis. The sensor's output is fed into an analog comparator whose
threshold is calibrated for proper operation.
The
I/0 distribution board notifies the operating system in the event high
operating temperatures are reached inside the module due to stopped fans,
clogged filters,
or high ambient temperature. The ENV Monitor circuit is
equipped with two over-temperature trip points located in the SCSI Device
Expansion Module,
CPU Module, and VME Expansion Module.
If the first trip point is reached in one of the SCSI Modules, an "interrupt
request" process is started. If the second trip point is reached before the
software finishes the shutdown process, the DC power is removed from that
SCSI Module.
The software
system shutdown continues until it stops or finishes, depending
on which SCSI device has the over-temperature problem. An
over-temperature LED on that failed SCSI device is lit to indicate failure. A
system over-temperature failure message should also appear on the system
console. The DC power is removed either by the user or the software for the
entire system. This
event should rarely occur because the temperature should
not rise fast enough to hit the second trip point.
If the first" over-temperature" trip point is reached on the CPU Module or any
VME Expansion Module, an interrupt is generated from the I/0 distribution
board to the CPU board, and the software shutdown process is started. If the
second trip point is reached before the software finishes the shutdown process,
the DC power is removed from the entire system. This prevents damage to the
system in case temperatures in any module rises too high.
Once the
system has powered down due to the over-temperature condition, an
operator is required to manually restart the system by turning the reset/power
on-off switch to the reset position located on the front panel. When the fault
S900RF/D4
2-9
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