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Using the IEC Debug Window and Watch Lists

Products: ACR9600, ACR9630, ACR9640

The IEC Debug Window provides a way to view values of variables in IEC PLC programs and to change and force the values.

If the IEC Debug Window is not visible, select View>IEC>Debug


Note that the Debug Window will be grayed out while the PLC is offline.

Variables can be added to the Debug Window while the PLC is online. Open the Resource Tab of the PLC Browser to view the list of variables within active programs. Double click or right-click on the variable to add to the Debug list.

WARNING: The maximum number of variables in the Debug window should be less than 16. If greater than 16, the on-line monitoring of programs will be very slow. Consider using mulitple, smaller watchlists instead of a single large one. See Working with Watchlists

Click on the value column of the variable to open the Set Variable dialog. This can be used to change values of variables while the program is running.

If a variable is forced, the value will be reset to the value specified at the end of each cycle (before writing to the outputs).

In the column "Force" of the IEC PLC Debug window, ACR-View will display if a variable is currently forced or not.
The action performed when pressing OK depends on which of the three buttons "set", "enable force" and "disable force" is selected:
-if the variable is currently not forced, "set" will once set the variable to the value specified. If the variable is modified by the application, this might have a very short effect only.

-"enable force" will force the variable to the value specified, i.e. set the variable to the specified value at the end of each cycle, "disable force" will have no effect
-if the variable is currently forced, "set" will disable forcing for this variable and set the variable once to the value specified, "enable force" will continue to force the variable, but with the value specified now, "disable force" will not set the variable, but only disable forcing for the variable

Please note the following:
-Forcing only resets the variable at the end of each cycle. Modifications during one cycle are possible and not prevented. 
-Forcing is not restricted to directly represented variables (AT %...) 
-Removing a variable from the watchlist will automatically disable forcing this variable

Working with Watchlists
The IEC Debug Windows list of variables can be saved to a so-called Watch List file. This allows for switching between different Watch Lists while being online.
-There is always a default Watch List file with the name .WL in the project root directory.
-While online, a Watch List is saved through the main menu command: IEC PLC->Watch->Save Watch List As...
The saved Watch List will then show up in the Browser's File pane. After saving, all subsequent modifications of the variable list will be stored in this Watch List.
-To restore a different saved Watch List simply open it by double-clicking it in the Browser. Or by choosing File->Open while the Watch List is selected in the Browser.
-An empty Watch List can be created by selecting File->New / Others / Watch List.


Save Watchlist as...


Create New Watch List


Selecting the active watchlist


Mar-2013  JW