PID.vi output range correction

[LuizMarques]

Hi all. 

I have a thermal box which uses a fan tô control temperature. Its working fine, but i Wonder if i'm doing the right thing

Fan is controlled via PWM. The output of the PID.vi must be in %duty cycle( 0 - 1)

However due to source limitation my fan is a 24V fan and my source only provides 12V

Therefore my duty cycle should be at least 50% ( 0.5) in order to start to work

So What i've done

My input on pid.vi compares temperature in °C and The setpoint in °C. For example 25°C for the setpoint and 24°C the real temperature. 

My output range of the PID.vi 0 - 100

And on the output of the PID. vi i scaled  The 0 - 100 to be 0.50 when is 0 and 1 when The output is 100.

Can i do that? Wouldnt be easier to set output range of the pid.vi to be 0.50 - 1?

Will it chance my PID gains? 

Tks

[GerdW]

Hi Luiz,

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@LuizMarques wrote:

So What i've done

Can i do that? Wouldnt be easier to set output range of the pid.vi to be 0.50 - 1?

Will it chance my PID gains? 

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It would help if you would attach your VI you have done instead of just some sentences…

Surely you should set the output range of your PID to the desired range.

And yes, surely this will change your PID gains, namely the P gain! You need to scale your PID gain by 0.005 (from 0-100% to 0.5-1.0: (1.0-0.5)/(100-0)!