Summary #

GHL devices feature a built-in RGB LED behind the GHL logo on the housing cover. It displays the current system status using color and blink codes — providing an at-a-glance overview without opening the software. This article explains the available display modes and the meaning of each color and blink pattern.

Applies to #

• ProfiLux 4 Series (incl. Industrial Line / IL)
• GHL Doser 2 / Maxi / 2.2 Maxi Series (incl. Industrial Line / IL)
• GHL Doser 3 / 3 Maxi Series (incl. Industrial Line / IL)

Display Modes #

Brightness and mode are configured on the General page, in the GHL-logo illumination section. The available modes are listed below; critical states (see Status Codes further down) are always shown regardless of the selected mode.

• Standard: Status notifications are shown blinking. Up to two can be shown simultaneously, alternating between each other.
• Standard without blinking: Status notifications are shown as a steady color instead of blinking. Only the highest-priority active notification is shown at a time. Note that a steady red light in this mode can indicate either an active alarm or a memory defect — open the software to determine the cause.
• Off: The logo LED is disabled. Status notifications are not shown (critical states still override this).
• Constant blue / red / green: The logo is permanently lit in the selected color. Status notifications are not shown (critical states still override this).

Status Codes #

Critical States (always shown, highest priority) #

These states are always displayed regardless of the configured display mode. They take priority over all other notifications and cannot be suppressed.

• Violet blinking: Device is booting.
• Red / Yellow alternating, blinking: Error — problem with the serial number or security key. Contact GHL support.
• Red constant: Error — memory defective. Contact GHL support.
• Yellow constant: Memory has been reset to defaults.

Status Notifications (Standard and Standard without blinking modes) #

The following states are shown in Standard and Standard without blinking modes, in priority order. In Standard mode they blink; in Standard without blinking mode they appear as a steady color. Up to two states can be active simultaneously in Standard mode — they alternate. In Standard without blinking mode, only the highest-priority active state is shown.

• Red: Alarm active.
• Yellow: Warning active. Only shown if no alarm is present.
• Green: Activity in progress, e.g. dosing or water change.
• White: Connecting to myGHL.
• Blue blinking / Blue constant: myGHL connected (blinking in Standard mode). If no other state is active and myGHL is not in use, the logo shows a steady blue as an idle indicator.