Allen-Bradley LOGIX 5000 Reference Manual page 240

Chapter 1 Process Control Instructions
240
Item Description
M11 Internal model CV1 - PV1
M21 Internal model CV2 - PV1
M31 Internal model CV3 - PV1
M12 Internal model CV1 - PV2
M22 Internal model CV2 - PV2
M32 Internal model CV3 - PV2
T Target response
C11, C22 Model-predictive function blocks (IMC) currently controlling PV1 and
PV2 to SP1 and SP2, respectively
Y11, Y21, Y31, Y12, Y22, Model outputs of M11, M21, M31, M12, M22, M32
Y32
Y1 PV1 prediction
Y2 PV2 prediction
CV1 (Reflux ratio) Controls PV1 (Top composition) in Coordinated Control (CC1).
CV2 (Stream Flow) Controls PV2 (Bottom composition) in Coordinated Control (CC2)
CV3 Drives the Target value through a target response.
Affects Math Status Flags
No
Major/Minor Faults
None specific to this instruction. See Index Through Arrays for Array-Indexing
Faults
Execution
Note that iin Structured Text, EnableIn is always true during a normal scan.
Therefore, if the instruction is in the control path activated by the logic, it will
execute.
Refer to Refer to Function Block Attributes.for more details including definitions
and general behavior for all Function Block instructions.
Rockwell Automation Publication 1756-RM006K-EN-P - November 2018