“Nobody changed anything” is the most common sentence in troubleshooting, and the compare tool is how you check it politely.
Online/offline compare
Connect to the CPU and run a compare: Portal shows every block that differs between the project on your disk and the program in the machine. Before touching a misbehaving machine, this answers the first diagnostic question — is the machine running the software we think it is? On service visits we compare before and after every intervention; the printout goes in the report.
Details worth knowing: time stamps alone do not mean functional difference (recompiles shift them), so use the detailed code comparison for blocks flagged different. Know-how-protected blocks compare by checksum only.
Project-to-project compare
Compare two project versions to audit a colleague’s changes, review a contractor’s delivery, or reconstruct what changed between the archive that works and the archive that does not. Combined with disciplined .zap archiving after every visit, this is version control for teams that do not have real version control.
The workflow we enforce
- Archive before changes (name: machine_date_reason).
- Change, test, compile.
- Compare against the morning archive — the diff list is the change documentation.
- Archive again, upload both to the project server.
Ten minutes of process converts “I think I only touched the infeed” into a list.
FAQ
Can the compare merge changes automatically? It can copy selected blocks between projects, which is a manual merge. For true parallel engineering, look at Multiuser Engineering instead.
Does it work for HMI? HMI compare exists but is coarser; for WinCC we rely more on disciplined archiving.
Zone Otomasyon documents every service intervention with before/after comparisons. Machines we maintain have history you can audit. Talk to us.