Monitoring the Ladder Diagram

You have connected to the target and downloaded the ladder diagram. It is currently executing on the hardware target. You can now "monitor" the ladder diagrams operation in EZ LADDER® (monitor mode)

Note: To be able to monitor a ladder diagram, the version currently opened in EZ LADDER® and the version (and ladder diagram) stored on the target must match name and version. If these do not match, the program must be downloaded to the target or the downloaded version must be opened in EZ LADDER® before any monitoring can occur.

Build information increments each time a program is compiled. A program can still be monitored as long as the actual program did NOT change (ie: the program was compiled again, but nothing was changed prior to the compilation).

Power Flow

With a program downloaded and executing, EZ LADDER® shows the status of the function and objects by coloring the links and objects (contacts and coils). Red indicates power flow (currently energized) while blue represents no power flow (not energized). Below shows EZ LADDER® connected to a target executing your lader diagram and it is indicating power flow.

Scan Time

In the Monitor mode, EZ LADDER® provides a display of the current scan time for the ladder diagram that is running. The scan time resolution is dependent upon the hardware target. Refer to the hardware target’s information for actual scan time resolution. Below shows the scan time of the ladder diagram that is currently executing.

Changing Variables

When running a ladder diagram in the Monitor mode, EZ LADDER® provides a method to change the variable values while it is operating. Internal variables, timer and counter variables may be changed.

To change a variable's value:

1. Double-click on the object. A dialog box appears with the current state or variable value. This box is editable and the value may be changed.
2. Change the value as needed and click OK. The changes take place immediately.

Note: The change does not affect the actual ladder diagram (in the Edit mode), only the executing program.

Changing a contact or coil variable (boolean) does not always have the desired effect. If the value is changed using the dialog box, the actual value will change only until the next scan and then will revert to the status of its coil (internal variables). Since the coil status is re-evaluated each scan, the contacts for the coil are updated and will override the variable change. Actual real world inputs cannot be changed at all.

Hover Boxes

In the Monitor mode, EZ LADDER® provides additional information in real time. Placing the pointer over an object, will cause a “hover box” to appear. This box provides additional information about the object the pointer is hovering over.

Stopping the Ladder Diagram Execution

The program execution may be stopped by pressing the STOP button on the tool bar.

Starting the Ladder Diagram Execution

The program execution may be started by pressing the START button on the tool bar.