Your machine runs, but the program's source file is gone: the person who wrote it has left, the original PC is dead, or nobody knows where the backup is. The day you need to modify the machine — or it breaks down — that program is nowhere to be found. It's one of the most common situations we meet in Algerian factories.
The short answer: in many cases the program can be read straight from the controller (if it isn't protected). When that isn't possible, we rewrite it from how the machine actually works. Either way, you leave with a documented backup.
1. Recover the program from the controller
The first thing to try: transfer the program from the controller's memory to a PC (an upload). This works on most brands: Siemens (S7-1200/1500 with TIA Portal, S7-300/400 with Step 7, LOGO!), Schneider (Modicon, Zelio), Omron, Fatek, LS (XGB/XGT), Delta, Xinje and Mitsubishi.
Two important points:
- Comments and variable names aren't always stored in the controller. On an S7-300/400 you recover the logic but often without the comments: the program is functional but less readable. On newer controllers (S7-1200/1500), the full project can be kept in the CPU.
- Protection can block the read. Password, know-how protection, locked blocks: we assess case by case.
2. If the program is protected or unreadable
When a direct read fails: check existing backups (USB stick, memory card, supplier email), contact the machine builder (OEM), or rewrite the program from the machine.
3. Rewrite the program from the machine
This is functional reverse engineering: understand what the machine does, then rebuild the program.
- List the inputs/outputs: sensors, actuators, safety devices.
- Observe the sequences: work order, timers, start/stop conditions.
- Write and test the program, step by step, with your operators.
The time depends on complexity: a few days for a small machine, more for a full line.
Stop it happening again: the backup
Keep the source file (not just the compiled version) and short documentation. Store a copy off the machine. Note the version at each change. That's what we hand back after every job.
How MTE can help
We program and recover Siemens, Schneider, Omron, Fatek, LS, Delta, Xinje and Mitsubishi controllers, and their HMI screens. Diagnosis within 24-48h, free quote, on site across Algeria. Need a hand? See our services or try our calculators.
👉 Lost program or a machine to modify? Send us the controller model and a photo of the panel on WhatsApp — we'll quickly tell you what's recoverable.