Emerson Exchange 365

Hello guys,

First of all I am sorry if my question is something very basic and I'm just wasting your time, but I tried to solve the issue and until now I got no positive results. I am trying to use the DeltaV model predictive control (MPC block) to control some parameters of a evaporator plant for my undergraduate thesis and the initial goal is to control the voltage value applied to a motor based on a level value; however, I always get an yellow circle with a question mark in it at the output. The control is working flawlessly when I use a PID control though. 

Thank you very much for your help!

Pedro.

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EDIT 1: Thank you very much for all the support, I'm sorry for the long time I took to answer but this week has been very busy. Anyway, I am attaching two images, the first one shows how I was connecting the MPC block, the interrogation mark was showing up over the MNPLT1 output. I read about it and it could mean that that output was OOS. As I couldn't figure out how to solve the problem, I decided to connect the MPC block directly to the main panel in which I have all the inputs and outputs as shown in the second picture below to see if it would work properly. Apparently, the problem was solved, but I still would like to use a separate module like the one shown in the first picture. Too clarify, the LT001 represents a level sensor and the SC001 represents the signal that goes to the frequency inverter responsible for the pump.

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EDIT 2: Hello guys, as I said in the last edit, the MPC block seemed to work fine when inserted in the same module as the inputs and outputs (Attempt #2). However, when I tried to use it as the input to a PID controller, I got a problem similar to the initial one described on the main post, a yellow question mark at the BKCAL_OUT of the PID block. Both the MPC and the PID seemed to work just fine when working alone, but I can't get them to work together. Another problem is that the PID keeps changing the actual mode to MANUAL although it is configured to CASCADE.

Again, thank you very much.

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EDIT 3: Yellow question mark problem was solved; however, MNLPT and BKCAL_IN values of the MPC block equal to zero.

Attempt #1: DIDN'T WORK - Yellow question mark over the MNPLT

Attempt #2: IT WORKED

Attempt #3: DIDN'T WORK - Yellow question mark over the BKCAL_OUT in the PID block.

Attempt #4: DIDN'T WORK - MNPLT and BKCAL_IN of the MPC block equal to zero

MPC Operate: