> For the complete documentation index, see [llms.txt](https://enless.gitbook.io/centre-aide/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://enless.gitbook.io/centre-aide/guides-installation/documentation-en/gateway-and-receivers/rx-modbus/led-behavior.md).

# LED behavior

RX MODBUS: LED behavior

The **RX MODBUS** has two sets of indicator lights (LEDs) that allow you to verify the operating status of the device without using the software interface.

## Internal LEDs (On the electronic board)

To access these LEDs, it is necessary to open the housing cover. They provide precise diagnostics of data flows.

<table><thead><tr><th width="80.2265625">LED</th><th width="106.01953125">Color</th><th width="118.07421875">State</th><th>Meaning</th></tr></thead><tbody><tr><td>A</td><td><mark style="color:green;">Green</mark></td><td>Flash</td><td><strong>Radio Reception</strong> : A message from a sensor has been received.</td></tr><tr><td>B</td><td><mark style="color:$warning;">Orange</mark></td><td>Flash</td><td><strong>Radio Transmission</strong> : The receiver has transmitted a message.</td></tr><tr><td>C</td><td><mark style="color:green;">Green</mark></td><td>On</td><td><strong>Power Supply</strong> : The board is correctly powered.</td></tr><tr><td>D</td><td><mark style="color:$warning;">Orange</mark></td><td>Flash</td><td><strong>TX Com</strong> : A communication message is transmitted (Modbus).</td></tr><tr><td>E</td><td><mark style="color:green;">Green</mark></td><td>Flash</td><td><strong>RX Com</strong> : A communication message is received (Modbus request).</td></tr><tr><td>F</td><td><mark style="color:red;">Red</mark></td><td>Off</td><td><strong>Not used</strong> : This LED remains off during normal operation.</td></tr></tbody></table>

## External LED (Closed housing)

A control LED is visible on the outside of the product, located near the power cable gland. It allows you to check the system status without dismantling the installation.

* Red LED (Status):
  * **Behavior** : One **flash** every minute.
  * **Meaning** : The receiver is active, the internal processor is functioning normally (Heartbeat).

{% hint style="info" %}
**Troubleshooting tip** :

* If the **internal LED C** is **off**, **check your power supply** (7.5 - 24VDC) and the **polarity** of the Red/Black wires.
* If the **LED D** and **E** do not blink **ever** when your controller sends requests, **check the serial wiring** (RS485/RS232) or the Modbus ID address.
  {% 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 by asking a question.

Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:

```
GET https://enless.gitbook.io/centre-aide/guides-installation/documentation-en/gateway-and-receivers/rx-modbus/led-behavior.md?ask=<question>&goal=<user_goal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.

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.