> For the complete documentation index, see [llms.txt](https://docs.lorric.com/qr/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.lorric.com/qr/fu-lt-english-v1/installation-and-setup/electrical-installation.md).
# Electrical Installation
{% hint style="danger" %}
**Safety First:** Do not perform wiring while the unit is powered on. Before any wiring work, turn off the power and disconnect the power supply.
{% endhint %}
{% hint style="danger" %}
**CRITICAL WARNING**: **Do not apply overvoltage to communication lines**\
The Modbus RS-485 communication lines (A/B) have a maximum rated voltage of typically 5 V. They must never be connected to or share continuity with the flowmeter's DC 24 V power lines. Incorrect wiring will instantly destroy the internal core components of the flowmeter. Damage caused by wiring errors is not covered under warranty. Always verify all wiring with a multimeter before powering on the device.
{% endhint %}
## **6-Pin Quick Connector Pin Definition**
* Connect the supplied cable to the power supply and the required communication interfaces. Unused wires must be insulated with protective material to prevent electric leakage or short circuits.
* Before opening the unit or performing any wiring, turn off the power and disconnect the power supply.
* Due to space limitations, the label on the side of the unit and the following diagrams show **wire pin definitions only**.
The 6-pin quick connector wire color assignments are defined as follows:
| | |
|---|
| 1 | Brown | 24 VDC (+) |
| 2 | Black | RS485 (B-) |
| 3 | Green | RS485 (A+) |
| 4 | Orange | NPN output (+) |
| 5 | Purple | 4~20mA (+) |
| 6 | Blue | 0 VDC (-) |
### 24V DC Power Wiring Diagram
* **Brown wire**: 24 VDC (+)
* **Blue wire**: 0 VDC (–)
### 4–20 mA Analog Output Wiring Diagram
* **Brown wire**: 24 VDC (+)
* **Blue wire**: 0 VDC (–)
* **Purple wire**: 4–20 mA (+)
### **NPN Output Wiring Diagram**
* **Brown wire**: 24 VDC (+)
* **Blue wire**: 0 VDC (–)
* **Orange wire**: NPN Output (+)
### **RS-485 Two-Wire Wiring Diagram**
* **Black wire**: RS-485 B (–)
* **Green wire**: RS-485 A (+)
{% hint style="info" %}
#### RS-485 Wiring Recommendations
* It is recommended to use **shielded 24 AWG twisted-pair cable** and connect devices in a **daisy-chain configuration**. Do not use star or ring wiring.
* For long cable runs, install **termination resistors** at both the master and the farthest device. A typical value is **120 Ω**, but the actual value should be calculated based on the cable specifications.
* If signal instability occurs, consider adding **bias resistors** at a point along the line.
* For the supplied 6-core cable, when used for RS-485 communication, **trim excess length** to minimize noise interference. Connect the shield braid to the main communication wires and **ground it**.
* In areas with heavy signal interference, the software may need to **poll multiple times** to receive a response. Implement a **repeated polling mechanism** in the communication program to distinguish between signal interference and actual device offline conditions.
{% endhint %}
***
---
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