CH Tech EM405D - Manual (Page 33)

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The function of each M-module trigger line is fully dependent upon the M-module. Refer to the
particular M-module’s documentation for further details.
4.5 FAN AND TEMPERATURE CONTROL
The EM405D contains an on-board temperature sensor placed near the M-module positions. The
current temperature inside the EM405D case can be determined by reading the Fan &
Temperature Control register of the EM405D. The TEMP field inside this register represents the
current temperature as read by the temperature sensor. To translate the TEMP value in to
degrees Celsius use the following equation:
°C = (TEMP – 281) / 4.6
The temperature sensor is also read by the firmware and used to control the variable speed fan.
When the fan is set to variable, the firmware constantly monitors the temperature and speeds up
the fan as the temperature rises. The variable fan is designed to maintain a maximum 20° C rise
in temperature from the ambient inlet air. The user may select the fan to remain full on at all
times by setting the VARF bit in the Fan & temperature Control register to a ‘1’.