|
Remote Sensor Selection (J12)
When configured to operate with a remote external temperature
sensor, choose a compatible SmartFan Sensor shown in the
SmartFan Catalog or at www.controlres.com/sensors.htm.
Control temperature is set through the I2C Bus.
Board-Mounted Temperature Sensor
In this configuration, the fan control signal is proportional to the
temperature at the sensor that is soldered to the Cirrus-6.
Control temperature is set through the I2C Bus.
Fan Tachometer Setting
Since fan tachometer circuits are designed with one, two or even
more pulse outputs per revolution, settings are listed in pulses
per minute (PPM) rather than revolutions per minute (RPM).
Given the fan’s speed under load (W) and the number of pulses
per revolution (N), use the following formula to select the trigger
speed (WA):
WA = W x N x 0.3
For example, a 3300-RPM fan with two pulses per revolution
would have a trigger speed of
WA = 3300 RPM x 2PPR x 0.3 = 1980 PPM.
Since the 2000 PPM trigger is closest, set tachometer speed to
2000 PPM.
The alarm trigger accuracy is +/- 10%.
The Cirrus-6 default factory setting is 2000 PPM.
Led Output Status Operation (J9)
LED outputs at J9 pins labeled R, G and K for their respective
cathode connections are provided as follows:
Red LED is energized for any fault condition.
Green LED is energized when no fault is present.
Two leaded and three leaded (common cathode) bi-colored
LEDs can also be used.
Alarm Logic (J11)
A dual isolated Alarm output is provided on J11. Pins 1A and
1B output is closed on no alarm. Pins 2A and 2B output is open
on no alarm. An alarm is also provided on power failure. These
outputs have a maximum on-state resistance of 50O. Maximum
sinking current is 100mA. A maximum of 230 VAC/VDC can
be applied to alarm terminals.
Fan Control Signal in any Alarm Condition
During the presence of any alarm condition, except power
failure, the full speed signal is applied to the fans.
Speed Override Input (J12 – Pin 4)
A logic level input is located on J12 that allows the user to
command the fans to full speed when a ground level is applied.
If this input is set to 3.3 VDC or open then the speed is set by its
normal operating mode. Refer to Figure 1(on the Installation page) for wiring details.
I2C Bus Protocol
The I2C Bus is configured as a slave device that can transmit
and receive data. When the Cirrus-6 is configured for I2C based
speed control, the user can write speed commands to the Cirrus-
6 and read all alarm status bits. When configured for
temperature based control the user can read all alarm status bits
from the Cirrus-6. Writing an I2C speed command changes the
control mode from temperature based to I2C based.
|
