• set PWM:
  AT+PWM=$value - set pwm value for all channels
  AT+PWM=($channel, $value) - set pwm $value for $channel
  

• read RPM info:
  AT?RPM - get RPM values from all channels
  

Each command must finish be new line character \n

example:
AT+PWM=50 - set all channel PWM to 50%
AT+PWM=(0,90) - set channel 0 to 90% PWM.
AT+PWM=(2,50) - set channel 2 to 50% PWM.
AT?RPM - get rpm value from all channels

Schematic will be available soon. PWM and tachometer pins can by connecting directly to arduino. Additional items are not necessary (resistor or transistors). here is connection info:

FAN PWM (OUTPUT):
PIN 9 - PWM output for channel 0
PIN 10 - PWM output for channel 1
PIN 3 - PWM output for channel 2

FAN tachometer (INPUT):
PIN 4 - RPM CHANNEL 0
PIN 5 - RPM CHANNEL 1
PIN 6 - RPM CHANNEL 2