> 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/fp-as510-paddle-wheel-flowmeter-manual-en-v2/install-and-set-up/mechanical-and-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 %}
## M12 8-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 M12 8-pin quick connector wire color assignments are defined as follows:
| Number | Color | Function |
| ------------- | ---------------------------- | --------------------------------------------------- |
| 1 | Black | RS485 (B-) |
| 2 | Yellow | OCT output (-) |
| 3 | Blue | VDC (-) |
| 4 | Orange | OCT output (+) |
| 5 | Green | RS485 (A+) |
| 6 | Purple | 4\~20mA (+) |
| 7 | Red | 4\~20mA (-) |
| 8 | Brown | 12-36 VDC (+) |
| Shielding net | White heat-shrinkable sleeve | (optional) Shielding net, please connect to ground. |
### DC Power Wiring Diagram
* **Brown Wire:** 12–36 VDC (+)
* **Blue Wire:** VDC (–)
### 4–20 mA Analog Output Wiring Diagram
* **Brown Wire:** 12–36 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. The DC power wiring is omitted from this diagram for readability. See the [DC Power Wiring Diagram](#dc-power-wiring-diagram) for details.
{% endhint %}
### **OCT PNP Output Wiring Diagram**
* **Brown Wire**: 12–36 VDC (+)
* **Blue Wire**: 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. The DC power wiring is omitted from this diagram for readability. See the [DC Power Wiring Diagram](#dc-power-wiring-diagram) for details.
{% endhint %}
### **RS485 Two-Wire Wiring Diagram**
* **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. The DC power wiring is omitted from this diagram for readability. 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. Route the shield braid along with the main communication wires and **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 %}
## **Device Pin Definitions**
Due to space constraints, the sticker on the side of the device only uses cable contact definitions.\
The number of the device contact and the cable contact is mirrored and symmetrical.\
Please see below device contact number:
Device Pin Map
***
## **How to replace a date battery of FP-AS510**
Applicable to all the models from HW v1.0.0 to v1.3.1
1.Take off top housing and then remove drained battery by the plastic ruler or other tools so that the device will not be scratched.
2.Put in a new CR2032 battery by the position with negative electrode (-) side towards battery base and positive electrode (+) side towards outside. Insert the battery on the side where there is a cable attached.
3\. Press the battery on the other side where there is no cable attached. Finish.
---
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