Hello Jenna,
first, you need to verify that contoller works properly. You do not have to worry about the correlation between full scale of the transducer and the range of the controller.
The first thing is to verify the ooperation in Open Loop mode. In open loop where the PID is bypassed (not used), set different volatge levels : 0, 1, 2, ...8,9,10 V and examine the tarnsducer readout range or voltage. If it is what it is and and 10 volt contrroler setpoint you have the maximum readout.
If the maximum readout (at 10 V) is way less than what you expect, then
1) verify with another refernce transducer the readout and make sure it is properly functional/calibrated
2)it could be the contr
oller is not opening/closing the valve all way,
or
3) in your system, this is what you get and the transducer used is way above the range of the system
In the closed loop mode, the PID should automatically adjusts the output voltage till the readout matches the set point. You do not to worry about the correlation between the two for a pproperly set PI D values.
The P I D values are +ve if increasing the controlller voltage increases the transducer readout,
and
negative if increasing the contoller voltage decreases the transducer readout
Assuming the contoller /PID is set to some voltage, When you block by hand the air flow, you expect the PID output to react, increase/or decrease , is this happening ? if true then it is doing what it is supposed to do. If it is changing slowly but in the right direction, then P or I value is too small.
If there is a dead band at the start of the controler, then you need to preset the controller to have a manual mode where you preset
the voltage out to a voltage value (the bias portion of the PID has to be set accordingly (the portion of I*(Error)
Hope this helps
