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Modbus Slave

The NexusIM gateway can act as a Modbus slave for a northbound Modbus master, such as a SCADA system. The master can read data collected from southbound devices through the Tags configured in Devices and Rules. Both Modbus TCP and Modbus RTU are supported.

modbus slave

  1. Enable or disable the Modbus Slave feature.

  2. Select the communication protocol:

    • Modbus TCP: configure the TCP port.

      TCP settings

    • Modbus RTU: configure the serial communication parameters, including interface, baud rate, data bits, stop bits, and parity.

      RTU settings

  3. Configure the Modbus Slave ID.

  4. Configure Modbus Slave points for Tags. Each point acts as a virtual register map.

add modbus slave

  • Select the source object. Source objects are data with Tags collected through Devices and Rules and are listed in the drop-down menu.
  • Configure the function code: 01 Read Coils, 02 Read Discrete Inputs, 03 Read Holding Registers, or 04 Read Input Registers.
  • Configure the start address.
  • Configure the data type.
  • Configure the read quantity.
  • Enable or disable the Modbus Slave point.

After configuration, the NexusIM gateway is ready to provide the mapped data to a Modbus master.