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).

Add a new Data Connector

2. Configure Connection Settings

Configuration of ModBus RTU Connector

• 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).

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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

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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.