Free tool · runs in your browser
Read the ladder logic
without a Studio 5000 license.
Drop a Studio 5000 export (.L5X) and read the program as
real rungs — contacts, coils, branches, timers and counters, with the actual tag
names, tag descriptions and rung comments. For the technician at the machine, the
OEM's customer, the night shift — anyone who needs to read the logic while
the one laptop with the license is somewhere else.
Everything runs locally in your browser — the program file is never uploaded.
How it works
- Export the program on any PC with Studio 5000 Logix Designer:
File → Save As… → file type “Logix Designer XML File (*.L5X)”.
That produces the complete project as open XML in seconds. (A partial export of
one routine — right-click it → Export… — works too.)
- Drop the file above. Parsing happens in your browser via WebAssembly —
on first use it fetches the ~10 MB engine, then works even offline. It is
the same parser that runs on the LineKeeper device, not a re-implementation.
- Read the ladder. Pick a program and routine, filter rungs by tag name or
comment, and read the logic the way it was written — including the rung comments
the original programmer left for exactly this moment.
What it shows — and what it doesn't. Ladder (RLL) routines render fully:
series and parallel branches, XIC/XIO contacts, coils, timers, counters, moves and
compares — unknown instructions still draw as labelled boxes, so any program stays
readable. FBD, structured text and SFC routines are listed but not drawn.
Source-protected logic stays protected: it renders as instruction boxes without
internals. The viewer is strictly read-only — it opens a file you exported yourself
and never connects to a controller.
Why a viewer, when the plant owns Studio 5000?
Because the license lives on one laptop, and the laptop lives with one person. When a
machine faults at 2 a.m., the electrician standing at it usually cannot open the
program at all — they call whoever has the seat. An .L5X
export is just a file: keep it with the machine's documentation, and anyone can read
the interlock that is holding the line, from any browser, with this page.
Need the tag values, not just the logic? The free
LineKeeper app browses every tag on a CompactLogix/ControlLogix live
— no L5X needed for that.
This viewer is the complement: the app shows what the values are, the export
shows why the logic drives them.
Is my PLC program uploaded to a server?
No. The viewer runs entirely in your browser (WebAssembly). The L5X file is
parsed on your computer and never leaves it — you can verify in the browser's
network inspector, or load the page and then disconnect from the network before
dropping the file.
Can it open an .ACD project file?
No. An .ACD is Studio 5000's compiled project format.
The supported input is the open XML export: in Studio 5000 Logix Designer,
File → Save As → choose “Logix Designer XML File (*.L5X)”. Anyone with
a Studio 5000 seat can produce it in seconds.
Does it show live values from the controller?
Not in the browser — a web page cannot speak EtherNet/IP. The viewer shows the
program as a readable snapshot. The LineKeeper device shows
these same rungs with live highlighting: contacts and coils turn green as the
machine runs, timers show their actual accumulators.
Which routine types are displayed?
Ladder (RLL) routines are rendered. Function block (FBD), structured text (ST)
and SFC routines are listed but not drawn. Source-protected routines and Add-On
Instructions render as instruction boxes without their internal logic.
Why would I need this if I have Studio 5000?
The license usually lives on one engineering laptop. This viewer lets a
technician, an OEM's customer or a night-shift electrician read the logic from any
browser — the export is just a file you can share within the plant.