Learn in 3 Minutes! Implementing PLC Recipe Functionality to Easily Handle Multi-Product Production Switches!

Do you remember that frustrating Monday morning when I first started my career? The factory received a new order with completely different product specifications, and the site supervisor was as anxious as a cat on a hot tin roof, while I—a rookie engineer—was thrown into the “battlefield.” Back then, every time we switched products, we had to re-enter dozens of parameters and adjust countless timers and counters; it was a nightmare!

Now, with the PLC recipe functionality, such scenarios have become a thing of the past. Just like the recipes in your kitchen, the “recipes” in industrial automation allow us to easily tackle the challenges of switching between multiple products. Today, I will unveil the mystery of this practical technology.

What is PLC Recipe Functionality?

In simple terms,a recipe is a collection of preset parameters used for quickly switching between different production process parameters. Imagine your coffee machine has different modes (American, Latte, Cappuccino), each corresponding to different water amounts, temperatures, and grind levels—this is the real-life version of a recipe.

In an industrial setting, a recipe may include:

Temperature setpoints
Pressure parameters
Time control points
Speed variables
Position data
Count setpoints

The Core Idea of Implementing PLC Recipe Functionality

A recipe is essentially the organization and invocation of data. In Siemens S7 series PLCs, I usually implement it using data blocks (DB):

 1DATA_BLOCK "Recipe_DB"
 2{ S7_Optimized_Access := 'TRUE' }
 3VERSION : 0.1
 4NON_RETAIN
 5   STRUCT 
 6      Recipe_Array : Array[1..10, 1..20] of Real;   // 10 recipes, each with 20 parameters
 7   END_STRUCT;
 8
 9BEGIN
10   // Preset values can be initialized here
11END_DATA_BLOCK

Do you remember that time on the beverage filling line when we had to switch between six different capacities from 300ml to 2L?The key lies in the design of the data structure. I created a two-dimensional array where the first dimension represents the recipe number and the second dimension represents the parameters. This way, the operator only needs to select the product number on the HMI, and all parameters are automatically loaded.

Practical Tips for Recipe Functionality

1. Choosing the Storage Location for Recipes

A novice colleague once asked me, “Master, where should recipe data be stored?” This question is crucial!

Data that needs to be retained during power outages: Store it in a non-volatile memory area (like Siemens’ retainable DB blocks)
Temporary test data: Can be placed in non-retainable memory areas
Core process data: Consider storing it on an SD card or backing up the PLC program itself

2. Data Security and Permissions

Once, in a chemical plant, an operator “took the initiative” to modify recipe parameters, resulting in a batch of products being scrapped. Since then, I always setparameter modification permission levels:

Operators: Can only select recipes, cannot modify
Process engineers: Can modify some non-critical parameters
Administrators: Have full modification permissions

3. Practical Code for Recipe Switching

 1// Recipe selection and loading program segment
 2IF "HMI_Recipe_Load_Cmd" THEN
 3    // Load the parameters of the selected recipe into the working area
 4    FOR #i := 1 TO 20 DO
 5        #Working_Parameter[#i] := "Recipe_DB".Recipe_Array["HMI_Recipe_Number", #i];
 6    END_FOR;
 7    // Reset load command
 8    "HMI_Recipe_Load_Cmd" := FALSE;
 9    // Set load completion flag
10    "Recipe_Loaded" := TRUE;
11END_IF;

Little Tricks in Practical Applications

Add Recipe Names and Descriptions: Don’t underestimate this! During a late-night fault, clear recipe naming can save your life. I usually add ASCII string descriptions for each recipe.

Recipe Version Control: Include a version number parameter in each recipe to ensure traceability of process changes.

Import/Export Functionality: Design an Excel format for recipe import and export functionality to facilitate data backup and migration.

Do you remember that time in the automotive parts factory? We used this functionality to copy the debugged recipes from the test line to six production lines, saving time on repeated debugging and achieving mass production a week ahead of schedule!

Conclusion

Mastering PLC recipe functionality is like equipping your automation system with the ability of a “Transformers”. It not only enhances production flexibility but also significantly reduces human errors. From the era when engineers had to manually modify programs to now, where operators can complete product switching with a mouse click, the progress of automation lies in these seemingly simple functions.

The next time you face the challenges of multi-product, small-batch production, don’t forget this powerful yet simple recipe functionality. It may not be flashy, but it is definitely a practical tool for enhancing the flexible production capabilities of your factory!