> 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-tx320-english-v1/installation-and-setup/electronic-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 %}
## 8-Pin Cable with Flying Leads 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 8-pin wire color assignments are defined as follows:
| Color | Function |
| ---------------------------- | --------------------------------------------------- |
| Black | RS485 (B-) |
| Yellow | OCT output (-) |
| Blue | VDC (-) |
| Orange | OCT output (+) |
| Green | RS485 (A+) |
| Purple | 4\~20mA (+) |
| Red | 4\~20mA (-) |
| Brown | 24 VDC (+) |
| White heat-shrinkable sleeve | (optional) Shielding net, please connect to ground. |
### DC Power Wiring Diagram
* **Brown Wire:** 24 VDC (+)
* **Blue Wire:** VDC (–)
### 4–20 mA Analog Output Wiring
* **Brown Wire:** 24 VDC (+)
* **Blue Wire:** VDC (–)
* **Purple Wire:** 4–20 mA (+)
* **Red Wire:** 4–20 mA (–)
{% hint style="info" %}
This function requires the brown and blue DC power wires to be powered. The following diagram is not showing power supply wiring for readability.
{% endhint %}
### **OCT NPN Output Wiring Diagram**
{% hint style="info" %}
This function requires the brown and blue DC power wires to be powered. See the [DC Power Wiring Diagram](#dc-power-wiring-diagram) for details.
{% endhint %}
### **OCT PNP Output Wiring**
* **Brown Wire**: 24 VDC (+)
* **Blue Wire**: 0 VDC (–)
* **Orange Wire**: OCT Output (+)
* **Yellow Wire**: OCT Output (–)
{% hint style="info" %}
This function requires the brown and blue DC power wires to be powered. See the [DC Power Wiring Diagram](#dc-power-wiring-diagram) for details.
{% endhint %}
### **RS485 Two-Wire Wiring**
* **Black Wire**: RS-485 B (–)
* **Green Wire**: RS-485 A (+)
{% hint style="info" %}
This function requires the brown and blue DC power wires to be energized. See the [DC Power Wiring Diagram](#dc-power-wiring-diagram) for details.
{% endhint %}
{% hint style="info" %}
### RS-485 Wiring Recommendations
1. 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.
2. 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.
3. If signal instability occurs, consider adding **bias resistors** at a point along the line.
4. The 8-core cable is shipped with the device, if used in RS485 communication, please trim the length, try to use a short wire to reduce noise interference. Connect the shielding net to the main communication wire shielding and then ground it.
5. 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 %}
---
# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.
## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:
```
GET https://docs.lorric.com/qr/fu-tx320-english-v1/installation-and-setup/electronic-installation.md?ask=&goal=
```
`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.