Find which object uses a tag before deleting it

What the blocked delete is telling you

The deletion message is a live-reference report. At least one object, on one screen, still points at the tag, so the tag database refuses the delete. Trying again changes nothing. Renaming the tag or retyping it before the reference is cleared leaves an object drawing from a name that no longer exists.

The manual search is real work. On a project with 8 screens, finding one tag by hand means opening all 8 screens and clicking through the objects on each. The cross-reference lookup does that walk for you and returns one row per screen and object that uses the tag.

Symptoms and what each one points to

• Delete refused, message names an associated object. At least one live reference remains. Trace it with the lookup before touching the tag database.
• Sort by Tag Name selected, but the results stay blank. The Tag Name field is still empty. Sorting organizes the lookup; selecting a tag fills it.
• No drop-down arrow in the Tag Name field, the window comes up short, a scroll bar runs along the bottom. The window is not laying out fully. The documented cause is the Windows desktop font size set to a custom value.
• A resize handle appears, but dragging the border changes nothing. The same font-size problem. Switching to a standard DPI such as 120 DPI leaves it in place.
• The results list screens you already edited. References remain on other screens. Re-run the lookup after every edit.

Run the cross-reference lookup

HMI packages document this tool under matching names: Tag Cross Reference in several, a Cross Reference form in one that also searches text strings, a Cross Reference button in another. They all answer one question: where is this tag used in the current project? The steps below use the documented menu path Tool > Tag Cross Reference; if your editor words it differently, the tool sits on a top-level menu under a name like that.

1. Open the project in the editor.
2. Open Tool > Tag Cross Reference.
3. Set the sort control to Sort by Tag Name.
4. Click the small down arrow at the right of the Tag Name field and select the tag. If the spelling is uncertain, open the Tag Database first and copy the exact name. A blank result list after sorting means the field is still empty; select the tag and the rows appear.
5. Read the rows. Each names the screen and the object that uses the tag.
6. Double-click a row. The editor opens that screen and highlights the exact object.

If the editor offers to re-create the cross-reference information before the lookup runs, accept it. Some editors build that index on demand, and the prompt is part of the normal flow. When the highlighted object hides under another object and swallows the click, select hidden HMI objects in the editor with the cross reference covers the selection trick.

Clear the references, then delete the tag

Work through the rows one at a time. Remove the object or re-point it to a different tag, whichever the logic needs. Clearing one row rarely clears the tag, so re-run the lookup after each edit until it returns no rows. Then open the Tag Database and delete the tag; with no references left, the deletion goes through and the warning is gone.

One safety point: if the tag drives something that moves, a conveyor start for instance, make the edit in the offline project and load it during a planned stop of 15 minutes or so, not while the line runs.

Check the result three ways: the lookup returns no rows for the tag, the tag database accepts the delete, and every screen that lost an object still opens cleanly. The HMI work stays in the editor. A board the whole crew reads, line status for example, is a separate job for a shop-floor signage screen, not for an HMI object.

When the tag picker is missing on a notebook

The hours go missing here, so it pays to know what was ruled out and in what order.

The symptom: the cross-reference window comes up short, a scroll bar sits at the bottom, and the Tag Name field has no arrow. A desktop PC opening the same project gets the full window with no scroll bar.

• Version. The desktop ran 2.3 and worked; the notebook ran 2.4 and did not; an upgrade to 2.41 changed nothing. Version was not the cause.
• Resolution. The notebook runs 1680 x 1050, and lowering the resolution was no option, because anything below the panel's maximum blurs the whole display.
• DPI. With a non-standard DPI set, this editor pops a window before it loads and asks you to move to a value it expects, such as 96 or 120 DPI. A switch to 120 DPI left the window broken, with a resize handle that dragged to no effect.

The setting that mattered is one level deeper: the desktop font size. Right-click the Windows desktop, open Properties, open the Appearance tab, and read the font size. On the notebook it sat on a custom value. The advice for this window was to set Normal if it was anything else; the size that restored the arrow on the notebook was Large fonts, also a standard choice. Either way, a standard size lays the window out and the drop-down arrow returns.

Changing the DPI and changing the desktop font size are two different controls on these systems, and only the font size mattered here. The same display-scaling class of problem shows up elsewhere in HMI work: the editor that draws objects but no text and dialogs clipped by legacy Windows fonts are both window-math and font-math disagreements, and a control at the edge of a window is usually the first casualty.

Check: the arrow is visible, opens the tag list, and a selection fills the rows. If the standard size makes other programs uncomfortable to read, set your preference back after the edit and keep a desktop PC for cross-reference work.

Example: freeing tag C1-Go on an eight-screen project

Take a project with 8 screens. Tag C1-Go refuses to delete: the editor reports it is associated with an object.

By hand: open each of the 8 screens and click every object. At a typical 30 objects per screen, that is 8 x 30 = 240 clicks, and one missed object sends you back to the start.

With the lookup: open Tool > Tag Cross Reference, set Sort by Tag Name, pick C1-Go in the Tag Name field. The rows list the screens that use it. Double-click a row, the screen opens with the object highlighted, and you delete that one object or re-point it. Re-run the lookup: no rows. Delete C1-Go from the Tag Database: accepted, no warning.

On the notebook the picker was hidden at 1680 x 1050 with the desktop font size on a custom value, and the earlier move to 120 DPI had changed nothing. Setting the font size to Large fonts brought the arrow back, and the same steps finished the job: one tool open, one selection, one object edited, one clean delete.

Recommendation: Before any tag deletion, open Tool > Tag Cross Reference, select the exact tag in the Tag Name field, and clear every listed reference until the lookup returns no rows; then delete from the tag database. Edit on a PC where the drop-down arrow shows. On a widescreen notebook that hides it, move the Windows desktop font size off the custom value to a standard size such as Large fonts first, then run the lookup there.

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