Compare two versions of a PLC program
Someone changed the program on the machine and nobody wrote down what. Or you have
Line3_old.ACD, Line3_final.ACD and Line3_final2.ACD and need to know which one runs on the
plant floor. Upload two versions and get a report of every difference, drawn the way you read
ladder logic.
What can be compared
Any two of these, in either order: Studio 5000 / RSLogix 5000 projects (.ACD), L5X and L5K
exports, and RSLogix 500 / RSLogix Micro projects (.RSS). The two files may be in different
formats, for example the .ACD from your laptop and an L5X a colleague exported, as long as they
are versions of the same kind of program (both Logix or both RSLogix 500).
What the report shows
- Programs, routines and ladder files that were added or removed.
- Changed rungs, matched by content rather than by number, so inserting one rung near the top does not mark everything below it as changed. Each changed rung is drawn twice, before and after, with its comment; added and removed rungs are drawn once.
- Comment-only changes: a rung whose logic is the same but whose comment was edited is listed as such.
- Structured text, function block and SFC routines line by line.
- Tags added, removed or changed (data type, description, alias target, member comments), data types, Add-On Instructions, modules and tasks.
- For RSLogix 500 projects also symbols and address descriptions, data file values and the data file list.
The changes are grouped by area, with a count of added, removed and changed items per area at the top.
Report formats
- PDF with the before and after drawings, for printing or attaching to a change record.
- HTML in one file, readable offline.
- Excel with one row per change: area, kind of change, program or routine, item, before and after.
The printout, viewer and tables of the first file come with the comparison.
How to upload
Put the older version in the first field and the newer one under "Second version to compare" (under "More options"). The report then reads from old to new: "added" means it is only in the newer file.
More about what this tool reads and writes: Rockwell PLC Program Viewer (ACD, RSS, L5X to PDF).