An AC500 CPU runs compiled code, so a usable upload is only possible if the project source was stored in the CPU at download time (V2: Online > Sourcecode download; V3: source download / project archive). With the source stored, open it from the PLC in Automation Builder, save it under a new name, log in and confirm that PC and PLC match before making any change.
- No stored source = no readable upload. Store it at every download
- Upload into a new project name; never overwrite your office copy blindly
- Log in after upload: no download prompt means PC and PLC match
- Keep dated archives with libraries in a central backup location
On site, the laptop with “the latest project” is often missing. Uploading from the CPU is the safety net, but only if someone stored the source. This lab shows both sides: how to upload, and how to make uploads possible for whoever comes after you.
Step 1: Know What the CPU Holds
| Stored in CPU | Created by | Can you edit it after upload? |
|---|---|---|
| Compiled program (boot project) | Download + Create boot project | No. It runs, but you cannot open it as ladder |
| Project source / archive | Sourcecode download (V2) or source download (V3) | Yes. Full project with comments and names |
| Retain / persistent data | Running program | Values only, read online |
| Project on SD card (if used) | Copied by you | Yes, open from the card |
Step 2: Store the Source in the CPU
- Log in to the CPU with your final project.
- V2 eco CPUs: choose Online > Sourcecode download.
- V3 eco CPUs: use the source download / project archive function in the Online menu.
- Note the date and version in your commissioning log.
Make “boot project + source download” one step in your download routine. It costs a few seconds and saves days on site.
Step 3: Upload the Project from the PLC
- Set the PC IP and check ping to the CPU (Lab 2).
- V2: in the programming editor choose File > Open and select the option to open the project from the PLC; enter the communication route to the CPU.
- V3: use Source upload from the File/Online menu and pick the CPU on the network.
- Save the uploaded project immediately as
SW_Conveyor_AC500eco_UPLOAD_2026-10-14. - Log in. If Automation Builder does not ask to download, the uploaded project matches what is running.
Step 4: Set Up a Backup Routine
| When | What to save | Where |
|---|---|---|
| After every download on site | Project archive incl. libraries, version + date in name | Laptop + company server |
| After commissioning | Archive, I/O list, drive parameter backups, HMI project | Machine documentation folder |
| Every 6 months (running machine) | Upload and compare with the archive | Server, flag differences |
| ID | Check | How to check | Pass criterion | Result |
|---|---|---|---|---|
| Upload test | ||||
| U-01 | Source stored | Sourcecode/source download done | Confirmation shown | |
| U-02 | Upload | Open project from PLC | Project opens with names and comments | |
| U-03 | Match | Log in with uploaded project | No download prompt | |
| U-04 | Archive | Save archive with date | File on server | |
Practice Exercise
Swap laptops with another student, upload their program from their kit, find the start/stop rung and add a comment to it, then log in and use online change. Explain why you must agree the change with the “machine owner” first.
Troubleshooting
| Symptom | Likely cause | Fix |
|---|---|---|
| “No source code in PLC” | Source never stored | Get the archive from the machine builder; store source next time |
| Uploaded project asks to download at login | Stored source older than running program | Do not download; investigate which is correct first |
| Upload fails with library errors | Libraries missing on the PC | Install the same Automation Builder version / libraries |
| Cannot find CPU | Network or route problem | Repeat the Lab 2 checks |
Frequently asked questions
Can I upload a program from any AC500 PLC?
You can read back a usable project only if its source was stored in the CPU or on its memory card. Without it you can see that a program runs, but not edit it.
How do I make sure my AC500 program can be uploaded later?
Store the source in the CPU at every final download: Online > Sourcecode download on V2 CPUs, or source download / project archive on V3 CPUs.
Will uploading stop the machine?
No. Uploading reads from the CPU; it does not stop it. Downloading or online changes are what affect the running machine.
What if the uploaded project differs from my office copy?
Treat the running version as the truth until proven otherwise. Compare both, document differences, then decide which one to keep.