To resolve Multiple-Input Multiple-Output (MIMO) systems whose inputs and outputs have different amplitude ranges, you can scale the data ranges of each input and output.

For example, consider the valves A and B in the following figure:

Figure 177. MIMO System Where Valve A and B Have DIfferent Amplitudes

Valves A and B operate between 0–100% and 50–60%, respectively. The pressure in the respective stream lines are PA and PB. If you assume that PB can be much larger than PA, you might need to normalize the range of operation of valve B for numerical robustness. You can use the following relationship to normalize the range of operation:

∆Level∆%A=∆Level∆%B-50·10

The SI Normalize VI ensures that all stimulus and response signals have a zero mean and unit variance over the sample data range used for model estimation. This process standardizes the range of the equation for all signals considered for model estimation. This data preprocessing step considers all inputs and outputs equally important from the numerical calculation viewpoint.