TIA Portal, Explained by Someone Who Uses It

Why this guide exists

Siemens manuals tell you what every option does. They rarely tell you which choice to make on a real machine, or why the program you inherited is painful to change.

I write TIA Portal for a living — mostly S7-1200 and S7-1500, on machines that have to run in production after I leave. Everything below comes out of that work. Where I have an opinion about how to structure a program, I say it is an opinion and explain the reasoning, so you can disagree with it on your own project.

If you are picking up TIA Portal seriously, or you have used it for years and want to compare habits, start with the structure articles and work outward.

Start here

• Why I’m Writing a Structured TIA Portal Series — what the series covers and the gap it is trying to fill.
• What a TIA Portal Program Is Actually Made Of — OBs, FBs, FCs and DBs — the map of the building blocks before the details.

How a TIA Portal program is structured and executed

• Organization Blocks — TIA Portal’s Execution Model — what actually calls your code, and when.
• Function Blocks vs Functions in TIA Portal — Code, State, and the Instance
• Data Blocks in TIA Portal — Why TIA Treats Data as First-Class Objects
• PLC Tags in TIA Portal and the Hardware Address Space
• Data Types and UDTs — The Type System in TIA Portal

Writing code your successor can maintain

This is where most of my opinions live.

• Why You Should Avoid Using Merkers (M Bits) in Modern TIA Portal Programs — hidden coupling, no reusability, and what to use instead.
• Multi-Instance vs Single-Instance Function Blocks
• Function Block Encapsulation — Clear Interfaces and Private State
• Understanding the InOut Interface Pattern in TIA Portal — using InOut with UDTs for a clean data architecture.
• How I Decide What Belongs in a TIA Portal UDT — how the decision holds up once the design starts changing.

Commissioning and getting the machine running

• TIA Portal Watch Tables — The Commissioning Tool You Are Underusing — including the Excel paste trick.
• Virtual Commissioning: 18 Fixes Found Before the Site Visit — what simulation caught before anyone travelled.
• TIA Portal HMI Firmware: The Cross-Version Trap That Wastes Hours on Site

Version control and modern practice

• The Complete Guide to Version Control for TIA Portal Projects — plain Git through to VCI in V20 and V21.
• How AI Is Changing Industrial Automation Development

Looking at the alternatives

If you want to see TIA Portal from the outside, I have two other guides written from the same TIA Portal starting point: SIMATIC AX, the text-based Siemens toolchain, and Codesys, the platform behind a large part of the non-Siemens PLC world.

And when the panel you need does not exist in anyone’s catalogue, there is Custom Devices — the electronics and operator interfaces I build myself.

Working on something similar?

I am Yuriy Mosiyenko — I design and program industrial control systems, mostly Siemens, as a one-person practice based in Bedford, Nova Scotia, working with customers across Canada. If you have a controls project you cannot staff internally, tell me what you are building.