# ModBus RTU

### Modbus RTU Data Connector

The **Modbus RTU Data Connector** enables Tricloud Nexus to interface with industrial equipment and systems that use the Modbus RTU protocol - a global standard for serial communication with PLCs, sensors, meters, and other field devices. Running at the Edge, this connector ensures reliable data acquisition directly from RS-232/RS-485 serial networks, even during network outages or offline scenarios. 

**Important:** The Edge device where the Modbus RTU Data Connector is configured must be equipped with a compatible serial data connection port (such as RS-232 or RS-485). This physical connectivity is required for direct communication with Modbus RTU devices at the Edge.

### Key Features

* **Edge-Based Operation:** Runs locally on Edge devices for real-time integration with Modbus RTU devices, ensuring data collection continues even if your site is offline.
* **Serial Connectivity:** Connects directly to Modbus RTU slave devices via serial ports (RS-232/RS-485).
* **Flexible Polling & Publishing:** Independently configure scan and publish intervals for optimal data throughput and efficiency.
* **Full Protocol Control:** Adjust baud rate, data bits, stop bits, and parity to match your device and network requirements.
* **Configurable Byte & Word Order:** Supports both little and big endian formats to ensure proper interpretation of complex values.
* **Unified Data Model:** All collected values are normalized into the Tricloud Nexus measurement format, ready for analytics, storage, and integration with cloud or enterprise systems.

### Configuring ModBus RTU Data Connector

#### 1. Add a New Connector

* Select the **Area** node where you want to configure Modbus RTU integration.
* Go to the **Data connectors** tab.
* Click **+ New data connector**, choose **Modbus RTU**, and enter a name (e.g., `ModBusRtuServer`).

<figure><img src="https://570593659-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FYMGRODsc2QD3N3wmfwTl%2Fuploads%2FiMGaiOzZFyvi3qD9kr9U%2Fimage.png?alt=media&#x26;token=477670b7-1309-483d-b39e-08dca8b41b43" alt="" width="563"><figcaption><p>Add a new Data Connector</p></figcaption></figure>

#### 2. Configure Connection Settings

<figure><img src="https://570593659-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FYMGRODsc2QD3N3wmfwTl%2Fuploads%2FBVEzCeTRFSbedBztTL9b%2Fimage.png?alt=media&#x26;token=49a22c64-e047-42a4-9052-eb83256260f6" alt="" width="373"><figcaption><p>Configuration of ModBus RTU Connector</p></figcaption></figure>

* **Name:** Friendly name for your connector (e.g., `ModBusRtuServer`).
* **Enabled:** Toggle to activate or deactivate this connector.
* **Slave Connection:** The serial port or IP/host for the Modbus RTU slave device (e.g., `123.10.10.123`). (Note: Serial port configuration may depend on your Edge hardware.)

#### 3. Configure Polling and Publishing

* **Scan Interval (ms):** How often (in milliseconds) the connector will poll the Modbus device for data (e.g., `1000` ms = once per second).
* **Publish Interval (ms):** How often (in milliseconds) collected data is published into Tricloud Nexus. Set this to match or exceed the scan interval to avoid data loss.
  * **Note:** The publish interval should not be smaller than the scan interval. In most cases, set publish interval equal to the minimum scan frequency. For heavy workloads, a higher publish interval can optimize communication and performance.

#### 4. Serial Communication Settings

* **Baud Rate:** Set the communication speed in bits per second (e.g., `9600, 14400, 19200`). Must match the setting on your Modbus RTU device/network.
* **Data Bits:** Number of data bits per character (e.g., `7` or `8`).
* **Stop Bits:** Number of stop bits per character (e.g., `1, 1½` or `2`).
* **Parity:** Parity setting for error checking (e.g., `Even`, `Odd`, or `None`).

#### 5. Byte & Word Order

* **Byte Order:** Set the byte ordering for multi-byte values (*Little* or *Big* endian).
* **Word Order:** Set the word ordering for multi-word values (*Little* or *Big*).

***

**Example Modbus RTU Connector Configuration**

| Setting               | Example Value   |
| --------------------- | --------------- |
| Name                  | ModBusRtuServer |
| Slave Connection      | 123.10.10.123   |
| Scan Interval (ms)    | 1000            |
| Publish Interval (ms) | 1000            |
| Byte Order            | Little          |
| Word Order            | Little          |
| Baud Rate             | 9600            |
| Data Bits             | 7               |
| Stop Bits             | 1               |
| Parity                | Even            |

***

### Best Practices

* **Match Serial Settings:** Ensure baud rate, parity, data bits, and stop bits match those of your Modbus RTU device and network. Incorrect settings will prevent communication.
* **Align Intervals:** Align scan and publish intervals to your operational needs - higher scan rates yield more detailed data but increase device and network load.
* **Validate Byte & Word Order:** Check your device documentation to select the correct byte and word order. Incorrect settings may produce swapped or inaccurate values.
* **Test with Live Devices:** Always test your connector with real hardware before deploying to production.
* **Buffering:** The connector will buffer data at the Edge during network outages, ensuring data is not lost and is sent to the cloud once connectivity is restored.
* **Use Descriptive Names:** Clear connector names help with management and troubleshooting.