Configure Splunk Edge Hub OS to communicate with electronic devices using the Modbus protocol

Note: For documentation on other necessary components for Splunk Edge Hub, see the Splunk App for Edge Hub documentation, Splunk Edge Hub mobile app documentation, and Splunk Edge Hub hardware documentation.

Splunk Edge Hub OS version 1.4.2 and Splunk OT Intelligence version 4.3.1 and higher supports communication with electronic devices that support the Modbus protocol.

You can configure a Modbus device by entering the IP address, port, addresses to read data from, and the polling interval.

Requirements and prerequisites

Complete the following requirements and prerequisites before configuring Splunk Edge Hub OS to communicate with electronic devices using the Modbus protocol.

Requirements

  • Have a device that supports the Modbus protocol.
  • Support for the Modbus protocol requires the following software versions:
    • Splunk Edge Hub OS version 1.4.2 or higher
    • Splunk OT Intelligence version 4.3.1 or higher
    • Splunk Edge Mobile app version 1.7.0 or higher

Prerequisites

Steps

  1. In the Edge Hub Advanced Settings, navigate to the Modbus tab.
  2. Select + Add.
  3. Connect and configure your Modbus device
    1. Configure your Modbus device on the Edge Hub. Provide the following details:
      1. IP Address: The IP address of the Modbus device.
      2. Port: The TCP port used for Modbus communication (default is usually 502).
      3. Polling Interval (seconds): How often the Edge Hub should poll the device for data.

    2. Add a Modbus device. Click the + Add Device button to define each Modbus device you want to read from. For each device, provide the following details:

      1. Device Name: A user-friendly label for display purposes only.

      2. Device ID: Also known as the Unit ID, this identifies the Modbus peer device. Note: The Edge Hub currently supports reading only from Holding Registers using Function Code 3.

    3. Configuring Register Address Ranges. After adding a device, define your address ranges. Provide the following details in order to specify which register ranges to read:

      1. Click the + Add button to create a new address range.

      2. For each address range, configure the following:

        1. Starting Address: The first register address to read.

        2. Ending Address: The last register address in the range.

        3. Unit: The data type of the register values (e.g., UINT16, INT32, FLOAT, STRING, etc.).

This configuration allows the Edge Hub to correctly interpret the raw Modbus data according to the expected register data types.

Your configured devices appear in the Modbus tab of the Edge Hub Advanced Settings page. To remove a configured device, select the x button next to the device you want to remove.

Download your Modbus configuration and upload it to another Splunk Edge Hub device

After completing a Modbus configuration for external sensors, you can download a configuration file to use it with other Splunk Edge Hub devices. Update the configuration file to replace values that are applicable to other Splunk Edge Hub devices.

Downloading and uploading an Modbus configuration file means you don't have to repeat the configuration steps again for multiple Splunk Edge Hub devices.

See Download a configuration file and upload it to another Splunk Edge Hub device to download and upload a configuration file to other Splunk Edge Hub devices.