Keysight PXIe Chassis Family User Guide 67
Monitoring Chassis Fan Speeds Chassis Cooling and Rack Mounting
Monitoring Chassis Fan Speeds
Both the M9018B and M9019A chassis contains three fans that are mounted on
the chassis rear panel and provide cooling for the chassis; the M9010A chassis
has two fans. The chassis allows you to monitor the speed of each fan in
revolutions per minute (RPM). You can also set a minimum fan speed threshold
such that, if any fan speed falls below this threshold, a fan speed alarm is
generated.
These monitoring capabilities are available using the Soft Front Panel (SFP) and
programmatically using the chassis drivers. In addition, the front panel Fan LED
provides information on fan speeds. Use of the SFP, the front panel Fan LED, and
the IVI drivers to monitor the chassis temperature sensors are described in the
following SFP and the front panel Fan LED diagram.
Setting the Fan Speed vs. Chassis Temperature Profile
The chassis allows you to control the fan speed vs. temperature profile. This is
done by specifying a chassis temperature at which the three fans will operate at
maximum speed. Maximum speed is achieved by the chassis supplying a drive
voltage to the fans with a 100% duty cycle.
For temperatures below the specified chassis temperature, the duty cycle of the
fan drive voltage will be less than 100%, which reduces the fan speed and the
fan noise. The reduction in fan speed is proportional to how far the chassis
temperature is below the specified chassis temperature. To ensure adequate
cooling at any temperature, the drive voltage to the fan will never drop below
40% duty cycle.
These fan speed vs. chassis temperature profile can be set using both the SFP
and programmatically, as described in the following diagram
Default Minimum Fan Speed Threshold Limit
The M9010A has a default minimum fan speed limit of 900 RPM. The M9018B
and M9019A have a default minimum fan speed limit of 1200 RPM. These default
limits are applied on chassis power on. The following diagrams apply to both
types of chassis, but the examples show the default minimum fan speed of 1200
RPM for the M9018B and M9019A.
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