Essential! PLC Program Version Management and Documentation Standards for Clear and Controllable Projects!

Do you remember the first time I faced that large filling line renovation project? At three in the morning, the production line was down, the client was standing behind me, and I was desperately comparing three different versions of the PLC program, trying to figure out which one was actually running. At that moment, I made a resolution: I will never let myself or my team fall into the nightmare of version confusion again.

Why is Version Management So Important?

Imagine you are making a complex dish. If you throw away the previous recipe every time you try to improve it, when the new recipe fails, you completely lose the chance to revert to the “working version.” This is what a PLC project without version management is like— a ticking time bomb that could explode at any moment.

I once saw this scenario in a food factory: engineers modified the program directly on the running PLC to quickly solve problems, without even making a backup. The result? One day, the equipment inexplicably started counting incorrectly, causing the entire production line to stop, because no one knew when the program had been modified or what had been changed. It took two full days to trace the cause!

Practical PLC Version Management Methods

1. Naming Convention—Your Lifesaver

Use the format “ProjectName-Date-VersionNumber-Modifier” to name your program files. For example:<span>FillingLine-20230512-V1.3-Zhang</span>. It seems simple, but this is the habit I am most grateful for during countless late-night troubleshooting sessions.

Once, a packaging line suddenly triggered an alarm and stopped. When I opened the control cabinet, I found the program was different from when I left. Thanks to the file naming, I immediately knew who modified it and when, and a single phone call resolved what could have been hours of debugging.

2. Change Log—Your Time Machine

Create a simple Excel spreadsheet for each project to record each modification:

• • Date and Time
• • Modifier
• • Brief Description of Changes
• • Reason for Changes
• • Affected Functional Modules

My mentor once told me, “A good memory is not as good as a bad pen, but a standardized change log is better than ten good memories.” During an equipment upgrade, it was by reviewing the change records from two years ago that we discovered a special timing logic customized by the client, avoiding a major failure.

3. Comments—Letters to Your Future Self and Others

Every functional block and key logic point should have clear comments. I habitually use the format “Modification Date + Modifier + Function Description.”

I remember once taking over an old project, and a piece of logic in the program left me puzzled—it seemed completely unreasonable but was essential. Fortunately, the previous engineer left a comment: “20180623-Li-Client equipment limitation, must reduce speed for 3 seconds before stopping, otherwise it will cause product accumulation.” This comment saved me a day’s worth of time!

4. Folder Structure—Making Searches No Longer a Nightmare

Establish a clear project folder structure:

ProjectName/
  ├── CurrentRunningVersion/
  ├── HistoricalVersions/
  ├── Documentation/
  │    ├── Design Specifications
  │    ├── IO Allocation Table
  │    └── Change Log
  └── Backups/

A fixed structure makes teamwork simple. I once worked on a collaborative project with multiple people, and because of this structure, even in emergencies, new engineers could find the required files within 5 minutes.

Implementation Tips

1. 1. Regularly back up to multiple locations—My habit is to ensure triple protection: local, USB drive, and cloud.
2. 2. Complete backup before major modifications—This is a painful lesson I learned after “deleting a line of code caused the entire system to crash.”
3. 3. Use difference comparison tools—such as the comparison feature in TIA Portal to quickly identify differences between two versions.
4. 4. Modular programming—makes modifications and maintenance easier and safer.

Conclusion

Do you remember the nightmare at three in the morning mentioned at the beginning of the article? If I had good version management at that time, I could have solved the problem in 15 minutes instead of spending 3 hours guessing and testing.

Version management may seem cumbersome, but it is actually a responsibility to your future self. Just like I often tell newcomers: “Spending an extra 10 minutes today to document may save you 10 hours of troubleshooting time tomorrow.”

When you receive a fault call late at night, a standardized documentation system is your most reliable ally!