No, you cannot edit Add-On Instructions (AOIs) online.
Understanding AOI Editing Limitations
Based on standard practices in Programmable Logic Controller (PLC) programming, specifically referencing the provided information:
You cannot edit AOIs online. All edits must be made offline and downloaded to the PLC.
This means that unlike some other components of a PLC program that might allow minor online edits, Add-On Instructions require a different workflow.
Why Offline Editing is Required for AOIs
When you need to modify an AOI, the following process is typically necessary:
- Offline Modification: The edits must be made in the programming software while disconnected from the live PLC or with the PLC in a state that allows major code changes (like a download).
- Compilation and Verification: The modified AOI is compiled and verified offline to ensure syntax and structure are correct.
- Download to PLC: The entire program, including the modified AOI, is then downloaded to the PLC. This often requires putting the PLC into program mode or stopping the process temporarily.
This offline-only requirement for AOIs ensures data integrity and consistency, preventing potential issues that could arise from attempting to alter complex, reusable code blocks within a running system.
Comparing Online vs. Offline Editing
| Feature | Online Editing | Offline Editing |
|---|---|---|
| AOI Edits | Not Supported | Required |
| Minor Logic Edits | Often Supported (e.g., Rungs) | Supported |
| Safety | Can be risky if not careful | Safer for major changes |
| Process Impact | Minimal for minor edits | Often requires process halt/pause |
Implications for Development and Maintenance
Understanding this limitation is crucial for PLC programmers:
- Planning: Factor in downtime or maintenance windows when planning modifications that involve AOIs.
- Testing: Thoroughly test modified AOIs offline or on a test rig before downloading to a production system.
- Version Control: Use robust version control for your PLC projects to track changes to AOIs and other code elements.
In summary, while online editing offers flexibility for minor tweaks, significant components like AOIs necessitate a more controlled, offline editing and download process to maintain system stability and reliability.
