What is the CXP file format?
A .cxp file is a compressed binary project file created and used by CX-Programmer, Omron's PLC (Programmable Logic Controller) programming software distributed as part of the CX-One automation software suite. The file stores the complete program for an Omron PLC: ladder logic diagrams, structured text programs, symbol tables, I/O unit configurations, memory allocations, and project comments.
.cxp is the compressed variant of the .cxt format - the same project data stored in a smaller file using Omron's proprietary compression. CX-Programmer targets Omron's CS, CJ, and CP series PLCs; for the newer NJ, NX, and NY series, Omron's Sysmac Studio software (using .smc2 files) is used instead.
Because the format is fully proprietary with no published specification, .cxp files can only be opened and transferred to hardware with CX-Programmer. The software runs exclusively on Windows and requires a valid CX-One license. A project may include an associated .opt file that stores backup configuration settings.
Version compatibility runs in one direction: a .cxp created in a newer version of CX-Programmer may not open in an older version, though older files open in newer software without issue. CX-Programmer v9.x, bundled in CX-One v4.x, is the current release as of 2024.
Security & safety
RISK: LOWCXP files are PLC program files; they cannot execute on a PC. They contain no scripts or macros. Risk is purely operational: uploading an incorrect CXP to a live PLC can disrupt or damage industrial equipment. Always verify on a test PLC or simulator first.
Format details
in a nutshellPrograms that open CXP files
Windows2 apps
CX-Programmer (CX-One)
Paid File → Open → select .cxp file. Requires valid CX-One license (dongle or software). Transfer to PLC via USB or serial with Online → Transfer.
CX-One suite
Paid CX-Programmer is bundled within CX-One; install CX-One to get CX-Programmer and open CXP files. Technical details
deep spec| Relationship to `.cxt` | `.cxp` is the compressed binary form of a project; `.cxt` is the uncompressed equivalent of the same data |
| Compression | Proprietary Omron algorithm; exact method not published |
| Byte order | Little-endian |
| Encoding | Binary; no human-readable representation |
| PLC families supported | Omron CS series, CJ series, CP series |
| Program content stored | Ladder logic, structured text, function block diagrams, symbol tables, I/O unit configuration, and comments |
| Companion file | `.opt` stores associated backup/restore configuration settings for the project |
| Version compatibility | Forward-compatible only; newer-version projects may not open in older CX-Programmer releases |
| Platform | Windows only - no macOS or Linux support |
| License requirement | Valid CX-One software license required to open projects and transfer programs to PLC hardware |
| Successor for NJ/NX/NY PLCs | Sysmac Studio (`.smc2` format) replaces CX-Programmer for newer Omron IEC 61131-3 platforms |
| Typical size | 10 KB - 5 MB depending on ladder logic complexity and data table size |
| Released | Late 1990s with CX-Programmer (CX-One suite) |
| Latest version | CX-Programmer v9.x (current as of 2024, bundled in CX-One v4.x) |
| Specification | www.ia.omron.com |
CXP conversions
Community Q&A
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