thanks bro,
yes i am using a SSR whose input control voltage range 3 to 32VDC and out put is 24-280AC rms and current input is 3.4mA @ 5VDC. i think it is fine with NI 6009.
But the thing is that i need to set the different speeds of the fan.i.e. i want to control the speeed of the fan as well. Mean to say wen i change the the volts form the NI device like 0 to 5volt from lab view knob the speed of the fan in out side will also need to change.
Can u tell me the device which i use between the fan and Ni device.If i chnge the voltage from the Analog output channel (3to 3.5 or 4) in the real world fan the speed increases.(Might be the input voltage to the fan increases from 20 to 40 or 40 to 60).
thanks