Chemical plant

A basic chemical plant is often made up of a series of silos for the storage of the reagents, a series of mixers for the mixing of the reagents in order to obtain a product, a network of pipes selectable by solenoid valves to set the recipe taking from the silos directing to mixers.

The basic structure of a silos shown in the image, useful as an object to design HMI.


The basic structure of a mixer is shown in the image, useful as an object to design HMI.



The main parts of a standard silo are:

  1. loading pump,
  2. drain pump,
  3. load cells,
  4. load valve,
  5. drain valve,
  6. vent chimney, (Italian:camino di sfiato)
  7. heating cables,
  8. valve position limit switch.

 The main parts of a standard Mixer are:

  1. electric motor for mixer rotation of the appropriate torque,
  2. Inverter if the process requires speed regime changes,
  3. mixer shaft with interchangeable cutting blades,
  4. product discharge pump,
  5. load cells, two or more load valves according to the production of the company, exhaust product download valve,
  6. vent chimney, heating cables,
  7. valve positioning limit switch.

Both, silo and mixer, must be represented in the PLC memory as a user-defined data type in which each field of the structure is one of the elements above.

User data type on PLC

A new type of data, for both silos and mixers, is defined in the project tree under the heading “PLC data types”.


Example of definition of the Silo Mixer fields

udt mixer

Example of definition of the Silo UDT fields


An array is created in the global data block for each of these new data types.


To access or manipulate the fields of the elements of the array, read the books advanced PLC programming ediz 2018 and Professional PLC programming ediz 2019 (work in progress) of the author Marco Gottardo, available on Amazon.

See the links below, on the page.

HMI recipes setup.

Each Mixer workstation, will be equipped with an HMI panel for setting the recipe. In this example, we will use a 15-inch comfort TP1500 model, which requires the installation of WinCC Advanced or WinCC Comfort in the TIA Portal V15. In the operator panel it will be necessary to set up graphic lists so that the elements change color according to the operating status.

bozza HMI chemical plant

To homogenize the HMI background to imported bitmap drawings, select the white background.

The whole project, with extensive explanations, is found in the two textbooks on sale on and on Amazon visible below. Text is in Italian but Step 7 programming and procedure can be well understand in any languages due to high number of figures explanation.

Copertina Esercizi PLC 2018 Amazon

buy the most complete workbook in the world in Amazon

Let’s Program a PLC!!! Esercizi di programmazione in TIA Portal V15 S7-1200/1500: quarta edizione 2018 (pubblicazioni di automazione industriale) (Volume 2) (Italian Edition) (Italian) Paperback – July 27, 2018
by dott Marco Gottardo PhD (Author)

  • Language: Italian
  • ISBN-10: 1724436465
  • ISBN-13: 978-1724436467

Advanced PLC Programming ediz.2018

Advanced PLC programming 2018

buy Advanced PLC programming on Amazon

Advanced PLC programming ed.2018: Pubblicazioni di Automazione Industriale (Volume 3) (Italian Edition) (Italian) Paperback – July 27, 2018
by dott Marco Gottardo PhD (Author)