Skip to main content

Modbus Slave

It refers to Elastel gateway act as Modbus Slave for Northbound Modbus Master (like SCADA) to fetch the data which gateway collected from south devices. The data was organized by “Tag Name” which configured in south device rule. It supports Modbus TCP or Modbus RTU communication protocol between slave and master.

Modbus slave

  1. Enable/Disable the Modbus Slave feature

  2. Select communication protocol, options TCP or RTU

    a) Modbus TCP, should configure the TCP port alt text

    b) Modbus RTU, should configure the serial com related parameters, including Interface, Baudrate, Databit, Stopbit, Parity
    modbus_rtu

  3. Configure the Modbus Slave ID

  4. Configure the Modbus slave point for tags, it’s like a virtual “Register” map. Modbus slave point

    1. Select the source object, source object is the data with Tag which collected from southbound device rules. All collected source objects will be listed under drop-down list
    2. Configure the Function code, Support 01-Read Coils, 02- Read Discrete Inputs, 03-Read Holding Registers, 04- Read Input Registers.
    3. Configure the Start Address
    4. Configure the Data Type
    5. Configure the read count quantity
    6. Enable/disable this Modbus slave point

After the configuration, the Elastel gateway is as a Modbus slave ready for Modbus master to acquire data.