Find where a signal is used
The Where used window lists every place in the project that refers to one signal. Open it before you delete or rename a signal to see what would stop working.
Before you begin
- The configuration editor is open on the Signals view. See A tour of the configuration editor.
Steps
1. Select the signal
Click the row of the signal in the signal list. Select exactly one signal: with no signal or several signals selected, the Where used button is unavailable and its tooltip says Select a signal.
2. Open Where used
Click Where used in the toolbar of the signal list. The window shows the full path of the signal at the top and Searching… while the server looks for references.
3. Read the references
The window groups the references. Only groups that have references are shown:
| Group | What it lists |
|---|---|
| Screens (n) | Each page, symbol, popup, layout or shared script that refers to the signal, with its kind, its name and the number of references, for example Page · Overview — 3 refs. Under it, up to three examples show the property and its text. |
| Server scripts (n) | Each server script that contains the signal path, with up to five matching lines, each shown as line n followed by the text of the line. |
| Calculated signals (n) | Internal signals whose expression, source or reset signal is this signal. Click a path to open that signal. |
| Alarm group rules (n) | Alarm groups with a path rule that refers to this signal, with the rule. |
| Other | The Alias of the signal, and the settings that are linked to the signal itself rather than to its path, each with a count. |
The settings under Other are:
| Label | Meaning |
|---|---|
| Bit derived from this signal | Bit signals taken from this signal; see Create bit signals from a word |
| Alarm using it as suppression condition | Alarms that use this signal as their suppression condition |
| Command using it as feedback | Commands that read their feedback from this signal |
| Alarm limit using it as deviation reference | Alarm limits that compare against this signal |
| Archive target | Archive assignments of the signal |
| Driver binding | The address bindings of the signal |
When nothing refers to the signal, the window says This signal is not used on any screen, script, expression or rule.
4. Check that the list is complete
The search is limited so that it stays fast in large projects: the screens are searched for up to 3 seconds and up to 100 screens are listed, and the rest of the report is also limited in time. When a limit is reached, an amber line says The list may be incomplete: the scan limit was reached. If the screens could not be searched at all, it says Screens could not be checked: with the reason. In both cases, do not take a missing entry as proof that the signal is unused.
Result
You know which screens, scripts, signals and settings use the signal, and whether the list is complete.
Good to know
- The settings under Other follow the signal when it is renamed. Screens, server scripts, expressions and alarm group rules refer to the path as text; renaming with Update references when renaming updates them. See Find, replace and rename signals.
- The import of a configuration table that deletes signals checks the deleted signals in the same way; see Import and export with Excel or CSV.