# HMI Overview

### Main Unit Functions

The main unit features a 3-line LCD, 16 characters per line. Each line displays different information:

* **Line 1:** Current page name and units
* **Line 2:** Actual measured data
* **Line 3:** Available key functions for the current screen

![](https://3404778090-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fi4ECt41Kyy9211OWazj4%2Fuploads%2FQzkPh1rlJkx4Tnfl3CJj%2Flcd-line.png?alt=media\&token=57bdc2cc-f077-4f00-9c04-2cb2d05641bc)

### **Button Functions**

The main unit has 4 buttons. The bottom line of the LCD (Line 3) shows the function of each button. Typically, the buttons are defined as follows:

<details>

<summary><strong>Button Functions (Click to Expand)</strong></summary>

The main unit has **four buttons**. The **bottom line (Line 3)** of the LCD displays the current function of each button. Under normal operation, the button functions are as follows:

* <img src="https://content.gitbook.com/content/i4ECt41Kyy9211OWazj4/blobs/BZuNjMgY75LH0onY5NtL/image" alt="" data-size="line"> **Blue Button -** Leftmost button: Return, exit, or save settings.

Gray Arrow Buttons:

* <img src="https://content.gitbook.com/content/i4ECt41Kyy9211OWazj4/blobs/Br88VpmnPLAPdutxVdZb/image" alt="" data-size="line"> **Left Gray Button:** Page up, increase value, or select item
* <img src="https://content.gitbook.com/content/i4ECt41Kyy9211OWazj4/blobs/3Dzp8nuxmHsaZ7LqBscw/image" alt="" data-size="line"> **Right Gray Button:** Page down, decrease value, or select item
* <img src="https://content.gitbook.com/content/i4ECt41Kyy9211OWazj4/blobs/sq6fX6r39JE0Au2hahAR/image" alt="" data-size="line"> **Orange Button:** Rightmost button: Enter settings, edit, or confirm selection

{% hint style="danger" %}
**Do not hold buttons for extended periods to avoid damage.**
{% endhint %}

{% hint style="info" %}
Button functions may change depending on the operation context to improve usability or prevent accidental presses.
{% endhint %}

</details>

<figure><img src="https://3404778090-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fi4ECt41Kyy9211OWazj4%2Fuploads%2FdeqC5V38IGY6KkURmaZr%2FFU-LT-buttons-en.png?alt=media&#x26;token=964c44e1-178d-444c-b323-c072d174bae7" alt=""><figcaption></figcaption></figure>

### **LCD Three-Color Backlight Function**

![](https://3404778090-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fi4ECt41Kyy9211OWazj4%2Fuploads%2FR51CaM8iivGne7CWtokm%2Fbackground-color.png?alt=media\&token=ba34a100-efe2-43f0-a006-bdcb338ec4f9)

The system provides a three-color backlight display. The **red backlight** is only activated when the alarm setting is **“On”**; if set to **“DND (Do Not Disturb)”** or **“Off”**, the backlight will remain off. The meanings of each color are as follows:

{% stepper %}
{% step %}

### **Green Backlight**

* System operating normally
* Displaying real-time information
* All data within normal range
  {% endstep %}

{% step %}

### **Flashing Red Backlight**

* Major abnormality (**Alarm A**) detected
* Refer to the [**Warning Details page**](https://docs.lorric.com/qr/fu-lt-english-v1/human-machine-interface-hmi/alarms-and-system-status) for more information
  {% endstep %}

{% step %}

### **Red Backlight**

* **Alarm B:** User-defined alert condition triggered
* **Alarm C:** Maintenance reminder condition reached
* Refer to the [**Warning Details page**](https://docs.lorric.com/qr/fu-lt-english-v1/human-machine-interface-hmi/alarms-and-system-status) for more information
  {% endstep %}

{% step %}

### **Orange Backlight**

* System operating normally
* Display currently on **Settings page**, not real-time information
  {% endstep %}
  {% endstepper %}

{% hint style="info" %}

#### **DND (Do Not Disturb) Mode**

* System detects abnormalities, but **red backlight remains off**.
* Example: **Alarm-A “4 Off Pipe”** triggers no backlight.
* Abnormalities still appear on the **Abnormalities page**.
* **RS485** connection still sends alarm signals.
* **OCT output** continues to signal alarms if configured.
  {% endhint %}