# Introduction the Human-Machine Interface (HMI)

### **LCD screen displays 3 rows of information**  <a href="#lcd-screen-displays-3-rows-of-information" id="lcd-screen-displays-3-rows-of-information"></a>

<figure><img src="https://1029883065-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F1LFXmYU1oAy08IUwsTZc%2Fuploads%2FQXkJDs4GkxzqhBXxAhHY%2Fimage.png?alt=media&#x26;token=529bea2a-64ae-437d-b661-5325a7193600" alt=""><figcaption></figcaption></figure>

Prolonged or excessive pressure on the buttons may cause damage.\
**Avoid pressing and holding buttons for extended periods.**

The main unit is equipped with **four control buttons**, and the **bottom line of the LCD screen** displays the current function assigned to each button.

* The **leftmost button** generally functions as **“Exit”** or **“Back”** to return to the previous screen.
* The **two central buttons** allow the user to **navigate between pages**, **adjust values**, or **select options**.
* The **rightmost button** typically serves as **“Enter”**, **“Confirm”**, or **“Set”**.

Please note that these definitions apply under **standard operating conditions**.\
In certain situations, the **button functions may be intentionally redefined** to improve usability or to reduce the risk of unintended operation.

{% hint style="info" %}
Prolonged or excessive pressure on the buttons may cause damage.

**Avoid pressing and holding buttons for extended periods.**&#x20;
{% endhint %}

<figure><img src="https://1029883065-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F1LFXmYU1oAy08IUwsTZc%2Fuploads%2F1ncwlkH21sA9lgBZGqL9%2Fimage.png?alt=media&#x26;token=7d353460-44a5-4be7-82f5-5b46d73cf6ea" alt=""><figcaption></figcaption></figure>

## **LCD Three-color large indicator lights** <a href="#three-color-large-indicator-lights" id="three-color-large-indicator-lights"></a>

<figure><img src="https://1029883065-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F1LFXmYU1oAy08IUwsTZc%2Fuploads%2FwlI9NcFR0FyvvPWOzLD9%2Fimage.png?alt=media&#x26;token=6073b281-647c-409b-9f5f-d9be2a1e1ce9" alt=""><figcaption></figcaption></figure>

### **LCD Backlight Status Indicators**

The LCD display is equipped with **three-colour backlighting**, with the following status definitions:

* **Green**: The unit is operating normally, displaying **real-time information**, and all values are **within the specified operational range**.
* **Flashing Red**: A **critical system alarm (Alarm A)** has been triggered.\
  Refer to the **alarm warning page** for further details.
* **Solid Red**:
  * **Alarm B**: A user-defined condition has been met — **operator attention is required**.
  * **Alarm C**: The **internal real-time clock battery** requires replacement.
* **Amber (Orange)**: The unit is functioning normally, and the screen is currently displaying **historical data or parameter configuration menus**.

## **Frequency Refresh Rate**

Due to the high-frequency nature of real-time flow measurements, the device **continuously refreshes the LCD display**.\
However, a **delay of approximately 0.1 seconds** may exist between the internal data acquisition and the displayed value.