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Using Watch Lists

What is a watch list?

A watch list is a user-defined list of project variables that are collected in one view for the purpose of monitoring their values. In online mode, you can write and force variable values in a watch list. Monitoring, writing, and forcing are handled the same way as in the online mode of the declaration editor. You can customize the format of the representation of floating-point values in the options for monitoring.

There are four, ready-to-use watch lists (Watch <n>) available in a project. Click View→ Watch.


If the expression is an interface reference, then it can be expanded. If the interface points to a global instance, then this global instance is displayed as the first entry below the reference. If the interface reference changes, then the displayed reference is collapsed.

Creating and editing a watch list (offline or online mode)

Requirement: The project is in either online or offline mode. It includes an application with declared variables that you want added to one of the four possible watch lists.

  1. Click View → Watch → Watch <n>.

    The Watch <n> view opens. It contains a blank table row.

  2. Double-click the field in the Expression column and type a variable to monitor, either manually or with the Input Assistant.

    Syntax: <device name>.<application name>.<object name>.<variable name>

    Example: "Dev1.App1.PLC_PRG.ivar"

    If you type the name of a structured variable, then the individual components are displayed automatically in other lines in online mode.

  3. Define all successive variables that will be monitored with this list. You can change the order by dragging items to a new location.

    The Execution Point, Type, Address, Comment fields are filled in automatically according to the variables declaration. The symbol before the expression indicates the type of variable: input variable (_cds_icon_input.png), output variable (_cds_icon_output.png), or "normal" variable (_cds_icon_variable_in_watchlist.png).


In online mode, you can also create or edit watch lists by clicking Add Watch in the context menu.

Adding variables by means of the Add Watch command (online mode)

Requirement: A project is open and running. It includes an application with declared variables that you want added to a possible watch list.

  1. Click View → Watch <n> to open the watch list.

  2. Place the cursor on a variable in the declaration or implementation part of a POU and right-click to choose the Add Watch command.

    The adds an entry to the list for the selected variable.

  3. You can add other variables in this way or by typing directly into the list in the Expression field as described above ("Creating and Editing…").

    The watch lists are updated immediately.


If a watch list is not open when you click Add Watch for a variable, then it is added automatically to the Watch 1 list.


Writing and forcing variable values is also possible in the watch lists. In online mode, the Prepared Value column is also available.