# E17 Endianness
### Definition
Sets the **byte order** for multi-byte data during RX (flow meter response) transmission. Options: **Big Endian**, **Little Endian**, **Register Swap**, or **Byte & Register Swap**.\
Default: **Big Endian**.
This setting **does not affect** Modbus ID, function code, CRC, or single-byte data.
For example, when returning flow and flow rate data, the flow value (e.g., 1000 decimal = 0x00007A44) is still sent **before** the flow rate. However, the **order of the four bytes representing 1000** changes depending on the selected format.\
(The diagram below shows each diamond representing one byte.)
Example
The following shows an example of using **Function Code 04** to request the flow meter to return **instantaneous flow (FS + value)** and **totalized flow (TF + value)**.\
(Each diamond in the diagram below represents one byte.)
* **First row:** Command sent from the Master. This is **not affected** by this setting. For details, refer to **Modbus Function Code 04**.
* **Second row:** Response from the flow meter with **Big Endian** configured. From left to right, bytes **0x01–0x08** and **CRC1–CRC2** are **not data** and are unaffected by this setting. The order of **instantaneous flow (FS + value)** and **totalized flow (TF + value)** in the response is also unchanged.
* Because Big Endian is selected, the four bytes of instantaneous flow (**FS3 → FS0**) are sent starting with **FS3**.
* The four bytes of totalized flow (**TF3 → TF0**) are sent starting with **TF3**.
* **Third row:** Response from the flow meter with **Little Endian** configured. From left to right, bytes **0x01–0x08** and **CRC1–CRC2** are **not data** and are unaffected by this setting. The order of **instantaneous flow (FS + value)** and **totalized flow (TF + value)** in the response is also unchanged.
* Because Little Endian is selected, the four bytes of instantaneous flow (**FS0 → FS3**) are sent starting with **FS0**.
* The four bytes of totalized flow (**TF0 → TF3**) are sent starting with **TF0**.
#### Modbus Converter for different formats
{% embed url="" %}
#### **Byte Order Explanation**
Assume a **32-bit value** is composed of 4 bytes (**A = most significant byte, D = least significant byte**) and stored in **two 16-bit registers**. ($$\mathbf{Reg1 = A B}$$, $$\mathbf{Reg2 = C D}$$)。
| **Type** | **Transmission Order (Hex)** |
| ----------------- | ---------------------------- |
| Big Endian | $$\mathbf{A~~B~~C\~D}$$ |
| Little Endian | $$\mathbf{D~~C~~B\~A}$$ |
| Mid Big Endian | $$\mathbf{C~~D~~A\~B}$$ |
| Mid Little Endian | $$\mathbf{B~~A~~D\~C}$$ |
### Notes
1. E17 Endianness can be modified via RS485.
2. The setting must match exactly with the Master’s configuration.
3. For details, see the [RS485 and Modbus RTU](https://docs.lorric.com/qr/fu-lt-english-v1/communication/rs485-modbus-rtu) Settings section.
### 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 %}
```
E17 Endianness Setting Steps
• From the main screen (green backlight),
press Orange Button (Setup) to enter settings (orange backlight).
• Use Gray Arrow Buttons to select E. Commute, press Orange Button (Enter).
• Use Gray Arrow Buttons to select E17 Endianness , 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).
```
### E17 Options, RS485 Values, Read/Write Commands, and Formats
| Opitons | Description | RS-485 Value |
| -------------------- | -------------------- | ------------ |
| Big Endian (Default) | | 0 |
| Little Endian | | 1 |
| Mid Big Endian | Register Swap | 2 |
| Mid Little Endian | Byte & Register Swap | 3 |
> Refer to the [Read/Write Memory List](https://docs.lorric.com/qr/fu-lt-english-v1/communication/modbus-rtu-protocol/read-write-memory-ram) for the Modbus command format. This parameter uses the Int16 data format.
