# A21 Auto Initialize
### Definition
Auto-detect fluid ultrasonic velocity to complete environmental parameter setup after mechanical installation, electrical installaton and parameter configuration.
The function starts only after pressing **Start**. Upon execution, it will automatically update the **Z03 (Auto Initialization)** settings.
{% hint style="info" %}
Currently, **A21** does not support Modbus read/write command operation.
{% endhint %}
### Notes
1. This step **must be performed when the pipeline is fully filled with liquid**. If **A21** is executed when the pipeline is not full, it may cause flow measurement errors and fluctuating readings. If this occurs, repeat **A21** under fully filled conditions.
2. The **Auto Initialization** of **A21** must be performed with the pipeline full. Whether the fluid is **flowing or stationary** does not affect the result.
3. **Each time the system is reinstalled or the pipeline size/material is changed, this function should be executed again.**
4. The **A21** function is equivalent to **Z03**, and the user may choose to execute either one.\
\&#xNAN;*(Z-series parameters are designed for quick setup, mainly during installation, consolidating multiple necessary parameters into a single series for faster completion.)*
### Operation Procedure
Button Functions (Click to Expand)
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:
* **Blue Button -** Leftmost button: Return, exit, or save settings.
Gray Arrow Buttons:
* **Left Gray Button:** Page up, increase value, or select item
* **Right Gray Button:** Page down, decrease value, or select item
* **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 %}
```
A21 Auto Initialize Setting Steps
• From the main screen (green backlight),
press Orange Button (Setup) to enter settings (orange backlight).
• Use Gray Arrow Buttons to select A. Measure , press Orange Button (Enter).
• Use Gray Arrow Buttons to select A21 Auto Initialize, press Orange Button (Enter).
• Use Gray Arrow Buttons to choose the options.
• Press Orange Button (Set) to confirm.
• Press Blue Button (ESC) to return to the main screen (green backlight).
```
