modbus_sample.conf

<source>
    type modbus           # Plugin name
    tag modbus.sensor1    # Tag for the data
    host 127.0.0.1    # ModBus host
    port 7000             # ModBus port
    polling_time 0,30     # Poll data at seconds separated by colons
    modbus_retry 1        # Retry counts for TCP connection to ModBus host
    reg_size 16           # Register bit size of ModBus I/O device in bit
    reg_addr 0            # Address of the register to read
    nregs 1               # Number of sequential registers to read [1-2]
</source>

<match modbus.sensor1>
    type copy
    <store>
        type stdout
    </store>
    <store>
        type mysql_modbus
        host 127.0.0.1
        username modbus
        password modbus
        database modbus_debug
        key_names dummy
        sql INSERT INTO dummy (d) VALUES (?)
        raw_data_type integer  # Raw data type [integer|float]
        max_input 10000        # Maximum value FROM ModBus I/O
        max_device_output 2000 # Maximum value TO ModBus I/O FROM sensor devices
        unit W/m^2             # Unit for the sensor device
    </store>
</match>