> 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-as310-paddle-wheel-flowmeter-manual-en-v1/troubleshooting/oct-pulse-debug-process.md).

# NPN pulse Debug process FP-AS310A

<figure><img src="/files/J6nthdFr6swwq7dZhlP4" alt=""><figcaption></figcaption></figure>

### **Environment and Parameter Verification**

1. Confirm the **main unit is powered on properly**.
2. Ensure the **data displayed on the diagnostic screen matches the communication data**.
3. Verify that the **NPN output function is enabled** and **correctly defined** (Parameter **E02**).\
   If **E02 is set to Paddlewheel Pulse** or **Pulse V2**, confirm this matches the intended configuration.
4. Check the **NPN default state**: Normally Closed (**NC**) or Normally Open (**NO**) as defined by Parameter **E01**.
5. Ensure the **wiring is correct**, the **external power supply is stable**, all **unused wires are insulated**, and the environment is **free of magnetic interference**.

### **Receiver Hardware, Circuit, and Software Verification**

1. Access **Parameter F03** to set the **number of pulses per second** for testing.\
   At the receiving end, check whether the corresponding pulses are received and if the **pulse count is accurate**.
2. Confirm **Parameter E03 (Pulse Width)** is **greater than or equal to the minimum pulse duration** required by the receiving device.
3. Check that **Parameter E14 (Pulse Unit)** value and unit **match the input requirements** of the receiving program.\
   Refer to the **parameter table** for detailed configuration.
4. Use **Parameter F04** to test the receiving end.\
   In the configuration screen:
   * Setting to **open** will disable conduction
   * Setting to **conduct** will enable conduction
5. Use a **multimeter in current mode**, connected between **NPN+ and the power supply’s positive terminal**, to check if **current flows when C0 = 1**.\
   Alternatively, use the **voltage mode** to measure between **NPN+ and NPN-** and verify whether a voltage drop **close to the power supply voltage** appears when **S0 = 1**.\
   If no proper output is observed on the first test, **double-check the power circuit**.

### **Results and Actions**

1. If the **NPN output is functioning**, and the **receiving device and software are also operating correctly**, but data remains abnormal, check for other potential causes such as **incorrect pipe size** or **paddlewheel malfunction**.
2. The **main unit may be damaged**. If another unit is available, conduct a **cross-test** to verify the **receiver, data processing program, and wiring**.
3. Record the **serial number of the unit**, **wiring diagram** (including all flow meter-related connections), and the **model/brand of the receiving device**, and **contact the manufacturer** for support.
4. Confirm whether the **receiving device, processing software, or wiring** may be at fault.

{% hint style="info" %}
Users should always **refer to actual on-site conditions**.\
For detailed troubleshooting and support, please **contact LORRIC directly** for further assistance.
{% endhint %}


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