This option designates whether touch-operation is disabled or not when the backlight burns out.
[Inhibit] option disables touch operation when the backlight burns out, which prevents the display unit from sending input signals to the PLC.
For the GP4000 series (except the GP-4100 series, GP-4201TM, and GP-4301TM), although detecting if the backlight is out is not available, if the screen does not display and the status LED is not in the breathing LED state, this indicates the backlight is burned out. When the screen does not display, always check the LED status and do not perform touch operations. (Breathing LED refers to the LED status where it repeatedly and slowly turns ON and then OFF.)
For details about the setting screen, refer to the setting guide.
M.16.2.2 Main Unit - Operation Settings
For models that cannot detect if the backlight is out, you cannot enable [Touch Panel Operation on Back Light Off]. For models that support backlight burnout detection, please refer to the following.
1.5 Supported Features
Go to offline mode and touch [Main Unit Settings] on the item changeover switch.
[Main Unit Settings] screen opens. Touch [Operation Settings].
[Operation Settings] screen opens. For the [Touch Panel Operation on Back Light Off] setting, select either [Operational] or [Inhibit].
[Exit] saves the changes and restarts the display unit.
Normally, the backlight burnout is detected by monitoring the backlight's current flow. However, the display unit may fail to detect this condition depending on the type of backlight problem, or the display unit may even detect the condition before the backlight burns out.
On display unit models that use two backlights, even if just one of the backlights is burned out, touch operations are disabled.
When the backlight burns out, the System Data Area's Status bit 10*1 turns ON.
When [Show System Menu] is set to [Lower Part] or [Upper Part], you can display the menu bar. (The screen is black, but the menu bar touch operations are enabled.)
If the backlight burns out while in offline mode, touch-panel operation is enabled, regardless of these settings.
*1 Bit +6 (when using the Direct Access method), and bit +1 (when using the Memory Link method), will turn ON