Simulation and Structured Text Generation Using PLC Coder

This example shows how to simulate and generate Structured Text for an MPC Controller block using PLC Coder software. The generated code uses single-precision.

Required Products

To run this example, Simulink® and Simulink® PLC Coder™ are required.

if ~mpcchecktoolboxinstalled('simulink')
    disp('Simulink(R) is required to run this example.')
if ~mpcchecktoolboxinstalled('plccoder')
    disp('Simulink(R) PLC Coder(TM) is required to run this example.');

Setup Environment

You must have write-permission to generate the relevant files and the executable. So, before starting simulation and code generation, change the current directory to a temporary directory.

cwd = pwd;
tmpdir = tempname;

Define Plant Model and MPC Controller

Define a SISO plant.

plant = ss(tf([3 1],[1 0.6 1]));

Define the MPC controller for the plant.

Ts = 0.1;   %Sampling time
p = 10;     %Prediction horizon
m = 2;      %Control horizon
Weights = struct('MV',0,'MVRate',0.01,'OV',1); % Weights
MV = struct('Min',-Inf,'Max',Inf,'RateMin',-100,'RateMax',100); % Input constraints
OV = struct('Min',-2,'Max',2); % Output constraints
mpcobj = mpc(plant,Ts,p,m,Weights,MV,OV);

Simulate and Generate Structured Text

Open the Simulink model.

mdl = 'mpc_plcdemo';

To generate structured text for the MPC Controller block, complete the following two steps:

  • Configure the MPC block to use single precision. Select "single" in the "Output data type" combo box in the MPC block dialog.

open_system([mdl '/Control System/MPC Controller'])

  • Put MPC block inside a subsystem block and treat the subsystem block as an atomic unit. Select the "Treat as atomic unit" checkbox in the subsystem block dialog.

Simulate the model in Simulink.

close_system([mdl '/Control System/MPC Controller'])
open_system([mdl '/Outputs//References'])
open_system([mdl '/Inputs'])
-->Converting model to discrete time.
-->Assuming output disturbance added to measured output channel #1 is integrated white noise.
-->The "Model.Noise" property of the "mpc" object is empty. Assuming white noise on each measured output channel.

To generate code with the PLC Coder, use the plcgeneratecode command.

disp('Generating PLC structure text... Please wait until it finishes.')
plcgeneratecode([mdl '/Control System']);
Generating PLC structure text... Please wait until it finishes.
PLC code generation successful for 'mpc_plcdemo/Control System'.

Generated files:
<a href="matlab: edit('plcsrc/mpc_plcdemo.exp')">plcsrc/mpc_plcdemo.exp</a>

The Message Viewer dialog box shows that PLC code generation was successful.

Close the Simulink model.


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