Student seeking assistance on how to do cascade control in TIA Portal

Here is the schematic of our program that we have right now.

Sorry it's so extensive; I had to screenshot everything into a Word document.  I didn't know how else to do it.

If you can take the time to look at it and tell me what you think I'd appreciate it.

Thanks again,

Adam

Question about tuning of cascaded controllers:

My system, the primary controlled variable is the Tank 2 level, and the secondary variable is Tank 1 level.

I understand that the secondary / inner loop is Tank 1 level in a loop with the PWM / pump control element, because the level of Tank 1 would have a faster response to disturbances in inflow than Tank 2 level would.

I also understand that when tuning cascaded controllers, the inner loop is tuned first.

When tuning the inner loop, what is the controlled variable for the purposes of tuning?  Is it Tank 1 level or Tank 2 level? 

Thanks again,

Adam

hdhosseini,

I forgot to tell you:  Last May my Senior Projects partner and I were able to pass the class.  We had been assigned to do cascade control, but we had trouble with our level sensors not working properly, so at the end we were just able to a single loop.

I just wanted to thank you very much for your time and your help.  It was greatly appreciated.

Thanks again,

Adam