Is there a method to view and edit the current value of a string within ladder logic? Instead of accessing the controller tags for manual editing, I would like the convenience of editing the string directly within my routine. One workaround I have found is transferring string data from one string to another. However, I am seeking a command within the ladder logic that allows me to edit the destination string directly within the routine.
To access the tag value in an instruction that refers to it, simply double-click on the tag (indicated by the blue arrow in the image). This allows you to easily view and edit the tag's value.
Thank you for your input. I am curious if there is a method to showcase just one string value in an instruction, eliminating the need to have both String tags for direct editing within the routine. This would streamline the editing process and enhance efficiency.
There is no straightforward method for achieving this in Rockwell PLCs, but PlantPAx by Rockwell offers a unique solution that may be of interest and utility. The following rungs demonstrate the approach taken by PlantPAx: JMP(SkipText)---CONCAT(string1,string2,string3)---CONCAT(string4,string5,string6)---LOWER(string7,string8)LBL(SkipText) The JMP and LBL commands prevent the execution of the CONCAT and LOWER instructions. The CONCAT instruction is utilized due to its ability to work with strings and accommodate 3 tags, thus improving efficiency. The LOWER command is recommended when only 2 additional strings are needed. An alternative approach is to use the same tag for both inputs in the instruction, resulting in only one string being displayed. It is important to note that regardless of the instructions used, they will not be executed. While this solution may seem unconventional, it aligns with Rockwell's methods for PLC programming. Therefore, utilizing a MOV instruction with the same tag for both source and destination is advised.
Using the "upper" instruction allows you to keep your text in uppercase format. Simply apply this tag in both the source and destination areas to ensure consistency.
In order to optimize your programming process, consider creating a MOV with the source and destination set to the same tag. This method works well when dealing with a single string. As long as certain conditions are met (such as ensuring instructions will not execute or aligning XIO and XIC inputs), you have the freedom to include any instructions necessary to access values effectively.
You're correct in noting the limitations in handling strings directly within ladder logic. It does indeed lack a simple functionality for directly modifying strings inside the routine. Because it was primarily designed for a control flow based on binary input/output, handling string data becomes a more complex task. Your transfer approach seems to be a reasonable workaround. Yet, while you can't directly edit a string value in the routine per se, you may consider invoking custom functions Import/Export ASCII or using a produced/consumed tag, if you're working with PLCs from different manufacturers. These might require a little more complexity but could offer some level of flexibility.
While I understand what you're looking to achieve, there isn't a specific command within ladder logic for directly editing strings within the routine itself. Your approach of transferring the data is a common practice. Direct manipulation of a string within ladder logic could potentiate unexpected outcomes, as it circumvents the usual checks in place. As a control engineer, I've found the IEC-61131-3 structured text programing language to be more flexible in terms of data manipulation, especially with strings. You might want to consider transitioning to that if your PLC supports it and the string manipulations are a significant part of your work.
✅ Work Order Management
✅ Asset Tracking
✅ Preventive Maintenance
✅ Inspection Report
We have received your information. We will share Schedule Demo details on your Mail Id.
Answer: Yes, there are methods to manipulate string values within ladder logic routines without needing to access controller tags for manual editing.
Answer: One workaround is transferring string data from one string variable to another within the ladder logic routine.
Answer: The discussion mentions seeking a command or function within ladder logic that enables direct editing of string values within the routine.
Join hundreds of satisfied customers who have transformed their maintenance processes.
Sign up today and start optimizing your workflow.