What is an ACD file?
An ACD file is a project file that contains information for programming Rockwell Automation Logix platforms. It includes instructions for controllers and processors. It is used for Logix platforms such as ControlLogix, CompactLogix, FlexLogix, SoftLogix5800, and DriveLogix systems.
Applications that can open ACD files include Rockwell Automation RSLogix 5000.
File Structure and Contents
Though the internal format of ACD files is not publicly documented, they are known to be compressed archive files. Internally, they include:
- Ladder Logic and Program Routines: The primary control logic used in industrial automation.
- Tag Database: Definitions of variables (tags) used across the controller logic.
- Configuration Data: Settings for communication modules, I/O, motion control, and specialty modules.
- Trend and Alarm Settings: Historical and real-time monitoring configurations.
- Documentation Artifacts: Descriptions, annotations, and user-added documentation.
How to Open and Use ACD Files
ACD files can only be opened and edited with Rockwell Automation software, specifically:
- RSLogix 5000 (for legacy versions)
- Studio 5000 Logix Designer (for modern versions)
Once opened, users can develop, simulate, debug, and download PLC programs to compatible Allen-Bradley hardware.
Export Options: ACD vs. L5K and L5X
While ACD is the default binary project format, Rockwell Automation software also supports exporting projects as:
- .L5K - ASCII-based representation suitable for version control systems.
- .L5X - XML format used for import/export and partial project handling.
Exporting to these formats can help teams manage changes more effectively using tools like Git or SVN.
Version Control Considerations
ACD files are not ideal for version control due to their binary nature and inconsistent size across saves. Even unchanged logic can result in different file hashes due to how metadata and session data are handled internally. If version tracking is important, exporting to .L5K or .L5X is recommended.
Tools and Parsing
Due to the proprietary nature of the ACD format, third-party support is limited. However, some community tools and libraries exist (like acd-tools) that can decompress or extract specific information. Use these cautiously, as they are unofficial and may not support all ACD versions.
Common Issues
- Incompatibility Between Software Versions: Newer ACD files may not open in older versions of RSLogix or Studio 5000.
- Corruption on Save: ACD files can sometimes become unreadable if a software crash occurs during saving. Regular backups are strongly advised.
- Version Drift: Users should be mindful of ACD files that balloon in size due to diagnostic data or historical logs included in the project file.
