CUBLOC STUDIO supports a “Monitoring” function that displays the operation status of LADDER LOGIC in real-time. You can enter or exit the monitoring mode by clicking the Monitoring ON/OFF switch on the toolbar at the top of the screen. Alternatively, pressing the F2 key will enter the monitoring mode.

The following is a screen capture during monitoring. Contacts in the ON state are displayed with a “Green Block,” and elements like timers and counters display their current values.

The status of I/O ports is displayed at the bottom of the screen. Ports that are ON are displayed in blue bold text. Only ports from 0 to 63 are shown.

To perform monitoring, the source code must exist. You must first download the program to the controller before you can start monitoring.

Editing and saving are not possible in LADDER monitoring mode. Additionally, downloading or displaying the BASIC debug window is unavailable while monitoring. Please ensure you turn off LADDER monitoring before performing other tasks.

When you want to view the contents of a specific relay or memory address, use WATCH POINTS. In an empty area of the LADDER, type two consecutive “apostrophes” followed by the relay number you wish to monitor. (Note: These are two single apostrophes, not a double quotation mark.) After downloading, the relay's status will be displayed at the watch point during monitoring mode.

A Double Word represents two words as a single value. By typing ''DD followed by the address, the value will be displayed as a Double Word. (This feature is supported from CUBLOC Studio V4.8 onwards.)

During online monitoring, you can use the “Forced I/O Setting” function on P contacts. Even if a hardware input is not received, setting a Forced I/O to ON will treat the input as being received. Output ports can also be forcibly set to ON or OFF.

To set this, double-click or right-click the corresponding contact in monitoring mode to display the popup menu, then select ON or OFF.

Disabling the force mode returns the ladder to its original logic execution. All Forced I/O settings are cleared when the power is turned OFF.

The Forced I/O function can be used when operation is hindered due to a sensor failure. By forcibly setting the problematic port to ON or OFF, you can continue to verify the PLC's operation.

Alternatively, it can be used for simple testing without hardware wiring or physical I/O manipulation. Forced I/O is available for ports 0 through 63.

During online monitoring, if you double-click (or right-click) a location displaying a D-area value, as indicated by the arrow in the figure below, the MODIFY window will appear.

You can change the contents of the D-area at will during operation. If another part of the ladder logic is updating that specific D-area, the changed value will not be maintained. This operation is executed only once and does not forcibly hold the value.

Go CUBLOC Ladder Logic home