Advanced PLC Tutorial: Siemens S7-1500 Recipe Management System Design

Hello everyone, I’m Tan Tan. Today, let’s talk about how to design a recipe management system using the Siemens S7-1500 PLC. This system allows you to easily manage the production parameters of different products, just like your smart rice cooker at home can store different cooking methods for various types of rice.

1. Basic Concepts of Recipe Management System

A recipe management system, simply put, is a functional module that can store and call production parameters for different products. Imagine you are cooking; different recipes are different “recipes,” and the PLC is your “electronic chef,” operating according to the selected recipe.

In industrial production, a recipe may include the following parameters:

• Raw material ratios
• Temperature settings
• Pressure control
• Stirring speed
• Processing time

Note: The accuracy of recipe parameters directly affects product quality, so the accuracy and safety of data are crucial.

2. Hardware Configuration

To implement the recipe management system, we need the following hardware:

1. Siemens S7-1500 PLC (CPU 1516-3 PN/DP)
2. HMI touch screen (such as TP1200 Comfort)
3. Storage card (at least 4GB)

The wiring diagram is as follows:

[PLC] <--- Ethernet ---> [HMI]
  |
  |--- Digital Input Module (for recipe selection)
  |--- Digital Output Module (for actuator control)
  |--- Analog Input Module (for sensor data collection)
  |--- Analog Output Module (for controlling inverters, etc.)

Note: Ensure that the IP addresses of the PLC and HMI are set correctly and are on the same subnet.

3. Software Design

We will use TIA Portal V16 for programming. The main design includes the following parts:

3.1 Data Block (DB) Design

Create a data block named “Recipe_DB” to store recipe data:

DATA_BLOCK "Recipe_DB"
{ S7_Optimized_Access := 'TRUE' }
VERSION : 0.1
   STRUCT 
      RecipeNumber : Int;  // Recipe number
      RecipeName : String[30];  // Recipe name
      Ingredient1 : Real;  // Ingredient 1 ratio
      Ingredient2 : Real;  // Ingredient 2 ratio
      Temperature : Real;  // Temperature setting
      MixingSpeed : Int;  // Stirring speed
      ProcessTime : Time;  // Processing time
   END_STRUCT;
BEGIN
   RecipeNumber := 1;
   RecipeName := 'Default Recipe';
   Ingredient1 := 50.0;
   Ingredient2 := 50.0;
   Temperature := 25.0;
   MixingSpeed := 1000;
   ProcessTime := T#10M;
END_DATA_BLOCK

3.2 Function Block (FB) Design

Create a function block named “Recipe_Management”:

FUNCTION_BLOCK "Recipe_Management"
VAR_INPUT
    RecipeNumber : Int;  // Recipe number to load
    LoadRecipe : Bool;  // Load recipe trigger signal
    SaveRecipe : Bool;  // Save recipe trigger signal
END_VAR

VAR_OUTPUT
    RecipeLoaded : Bool;  // Recipe load complete signal
    RecipeSaved : Bool;  // Recipe save complete signal
END_VAR

VAR
    RecipeDB : "Recipe_DB";  // Recipe data block instance
END_VAR

BEGIN
    // Load recipe
    IF LoadRecipe THEN
        // Code to read data from the storage card should be here
        // For simplicity, we directly assign values
        RecipeDB.RecipeNumber := RecipeNumber;
        RecipeDB.RecipeName := CONCAT(IN1 := 'Recipe ', IN2 := INT_TO_STRING(RecipeNumber));
        RecipeLoaded := TRUE;
    ELSE
        RecipeLoaded := FALSE;
    END_IF;
    
    // Save recipe
    IF SaveRecipe THEN
        // Code to write to the storage card should be here
        // For simplicity, we just set a flag
        RecipeSaved := TRUE;
    ELSE
        RecipeSaved := FALSE;
    END_IF;
END_FUNCTION_BLOCK

3.3 Main Program (OB1) Design

Call the recipe management function block in the main program:

ORGANIZATION_BLOCK "Main"
VAR
    RecipeManager : "Recipe_Management";
END_VAR

BEGIN
    // Call the recipe management function block
    RecipeManager(
        RecipeNumber := "Input_RecipeNumber",
        LoadRecipe := "Input_LoadRecipe",
        SaveRecipe := "Input_SaveRecipe",
        RecipeLoaded => "Output_RecipeLoaded",
        RecipeSaved => "Output_RecipeSaved"
    );
    
    // Execute production process based on loaded recipe
    IF "Output_RecipeLoaded" THEN
        // Set temperature
        "Output_Temperature" := "Recipe_DB".Temperature;
        // Set stirring speed
        "Output_MixingSpeed" := "Recipe_DB".MixingSpeed;
        // ... other parameter settings
    END_IF;
END_ORGANIZATION_BLOCK

Note: In practical applications, consider safety issues when switching recipes, such as ensuring the current production cycle ends before switching recipes.

4. HMI Design

Design the following screens on the HMI:

1. Recipe selection screen
2. Recipe parameter display and edit screen
3. Production status monitoring screen

Key point: Ensure correct data interaction between the HMI and PLC; HMI tags can be directly linked to the PLC data blocks.

5. Practical Application Case

Assuming we apply this recipe management system on a cookie production line:

1. The operator selects the “Chocolate Cookie” recipe through the HMI
2. The PLC loads the corresponding recipe data
3. The system automatically sets the ratios of flour and chocolate, oven temperature, stirring speed, and other parameters
4. The production process begins, with the PLC controlling various actuators based on the recipe parameters
5. After production is completed, the production report can be viewed through the HMI, and the recipe can be adjusted and saved if necessary

6. Common Problems and Solutions

1. Problem: Sudden changes in production parameters when switching recipesSolution: Implement gradual transitions or only allow switching at safety points (e.g., end of production cycle)

2. Problem: Loss of recipe dataSolution: Regularly back up recipe data to the storage card and implement redundancy storage if necessary

3. Problem: Unauthorized recipe modificationsSolution: Implement user permission management; critical operations require a password

Safety Reminder: In food production lines, ensure all materials and parameters meet food safety standards. Regularly check and calibrate sensors to ensure the accuracy of recipe execution.

Practical Suggestions

1. Start with simple recipes and gradually increase complexity
2. Use simulation software (such as PLCSIM Advanced) for preliminary testing
3. When testing on actual hardware, first use water instead of actual raw materials for debugging
4. Keep a historical record of each recipe modification for easy tracking and rollback
5. Regularly train operators to ensure they understand the workings of the recipe management system

Remember, a good recipe management system not only improves production efficiency but also ensures the consistency of product quality. With more practice, you will soon become a master of recipe management!