Simulation and Structured Text Generation Using Simulink PLC Coder

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

Set Up Environment

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

cwd = pwd;
tmpdir = tempname;
mkdir(tmpdir);
cd(tmpdir);
[SUCCESS,MESSAGE,MESSAGEID] = copyfile(fullfile(cwd,'mpc_plc_codegen.slx'));

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;   %Sample 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_plc_codegen';
open_system(mdl)

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

• Configure the MPC block to use single-precision data. Set the Output data type property of the MPC Controller block to single.

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

• Put the MPC block inside a subsystem block and treat the subsystem block as an atomic unit. Select the Treat as atomic unit property of the subsystem block.

Simulate the model in Simulink.

close_system([mdl '/Control System/MPC Controller'])
open_system([mdl '/Outputs//References'])
open_system([mdl '/Inputs'])
sim(mdl)

-->Converting model to discrete time.
-->Assuming output disturbance added to measured output #1 is integrated white noise.
-->"Model.Noise" is empty. Assuming white noise on each measured output.

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.
### Generating PLC code for 'mpc_plc_codegen/Control System'.
### Using <a href="matlab:configset.showParameterGroup('mpc_plc_codegen', { 'PLC Code Generation' } )">model settings</a> from 'mpc_plc_codegen' for PLC code generation parameters.
### Begin code generation for IDE <a href="matlab:configset.showParameterGroup('mpc_plc_codegen', { 'PLC Code Generation' } )">codesys23</a>.
### Emit PLC code to file.
### Creating PLC code generation report <a href="matlab:web('/tmp/Bdoc24b_2725827_1599930/tpcd777b3e_b7f1_41c8_b46b_99d07a2a105d/plcsrc/html/mpc_plc_codegen/mpc_plc_codegen_codegen_rpt.html')">mpc_plc_codegen_codegen_rpt.html</a>.
### PLC code generation successful for 'mpc_plc_codegen/Control System'.
### Generated files:
<a href="matlab: edit('plcsrc/mpc_plc_codegen.exp')">plcsrc/mpc_plc_codegen.exp</a>

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