How to compare two Studio 5000 projects and see what actually changed
The machine builder sends "the latest program" after a service visit. Their note says "minor fixes". Before it goes on your line, you want to know which rungs those were.
Studio 5000 installs a separate Logix Designer Compare Tool that compares two .ACD or .L5X files and lists differences by component. It needs Studio 5000 on the PC. Without it, you can diff two L5X exports as text, which works but is noisy. Rungview compares two projects rung by rung: it lists changed, added and removed rungs with the old and new ladder drawn one above the other, plus tags that were added, removed or changed type.
With Rockwell's Compare Tool
The Logix Designer Compare Tool comes with Studio 5000. Point it at two projects and it produces a tree of differences: tags, routines, rungs, module properties. It is thorough, but it needs a Studio 5000 installation, and the output takes practice to read.
As a text diff
Export both projects as L5X and run them through a diff tool or Git. Changed rungs show up as changed neutral text lines. The catch is noise: export dates, tag values and element order also change, and a long rung that differs by one contact appears as one long changed line.
In Rungview
Open the first project, then Compare with… the second. Rungview matches routines by program and name and aligns rungs inside each one, so an inserted rung doesn't make everything below it look changed. For each difference you see the A and B rungs drawn as ladder, one above the other. Tag changes are summarised in a table. Compare is part of Pro, for .ACD and .L5X alike.
What to look for in an OEM update
- Changed interlocks: any XIC or XIO on a safety, guard or permissive tag that was removed or bypassed.
- New timers and presets: changed preset values change machine behaviour without changing structure.
- New tags: often the sign of a new feature, or of test bits left in.
- Removed rungs: make sure the function went somewhere rather than away.
See what the update changed
Open both versions and read the differences as ladder. Pro is $9 a month or $59 a year.
Get Rungview
.ACD and .L5X · read-only, never touches the PLC · files stay on your computer · cancel Pro any time.
FAQ
Can I compare an .ACD with an .L5X?
Yes. Rungview reads both and compares the logic, not the file format.
Does compare show changed tag values?
It shows tags added, removed and retyped. Rung changes include changed literal values such as timer presets.
Can I export the comparison?
Print it to PDF from the compare view and attach it to the change record.