Modbus TCP Collector
Basic settings
These settings are used by the collector to successfully connect to the Modbus server.
Endpoint
Description: The location of the Modbus server. Required: yes Example: tcp://localhost:502
This configures the IP address and port on which the Modbus server is listening.
ByteOrderDefault
Description: The default Modbus byte order to interpret the register bytes and register sequence. Required: yes Default: AB-(CD)-(EF-GH) Options: AB-(CD)-(EF-GH) | BA-(DC)-(FE-HG) | (HG-FE)-(DC)-BA | (GH-EF)-(CD)-AB
This defines how bytes and registers are ordered when decoding multi-register values. You can override this per measurement with a custom order (for example, AB-CD-FE-HG).
Advanced settings
ReadTimeout
Description: The Modbus read timeout in milliseconds. Required: no Default: 5000
Measurement settings
The measurement settings reflect the configuration possibilities for mapping a measurement to a Modbus address range and function code.
Address
Description: The Modbus address to start reading registers from. Required: yes Default: 0
CollectionType
Description: The way this measurement should be collected from the Modbus server. Required: yes Default: polled Options: polled | monitored
Checkout the data collection methods section for more information.
SlaveID
Description: The Slave ID is a string of two hexadecimal characters referring to the Modbus slave to request data from (for example, broadcast is ff). Required: yes Default: ff
CollectionInterval
Description: The interval in milliseconds at which this measurement should be collected. Required: no Default: 5000
CollectionOffset
Description: The offset in milliseconds, relative to the 0th second of a minute, at which this measurement should be collected. Only relevant for polled measurements. Required: no Default: 0
RegisterType
Description: The Modbus register type to read. Required: yes Default: Input Register Options: Coil | Discrete Input | Input Register | Holding Register
ModbusDataType
Description: The datatype of the Modbus registers to read. If the register type is Discrete Input or Coil, only boolean is allowed. Required: yes Options: boolean | uint16 | int16 | uint32 | int32 | float32 | uint64 | int64 | float64
ByteOrder
Description: The Modbus byte order to interpret the register bytes. Optional and overrides the collector’s ByteOrderDefault. Required: no Default: Default Options: Default | AB-(CD)-(EF-GH) | BA-(DC)-(FE-HG) | (HG-FE)-(DC)-BA | (GH-EF)-(CD)-AB
Data collection methods
The Modbus collector has 2 methods to collect measurement data, which are referred to as the collection type of a measurement.
Polling
Polled measurements are read every x milliseconds (minimum of 1000 ms), which is the collection interval. This data collection method should be used for measurements whose value changes regularly over time. Configure the interval depending on how frequently you want to collect data points for this measurement.
Monitoring
Monitored measurements collect data on every change of the measurement’s value. This data collection method polls the measurement at the minimum interval and notifies the collector whenever a change occurs. Typically, monitored measurements are configured for boolean or string data types that indicate an equipment’s state, for example, a valve that opens or closes only a few times per hour.
Collector health
Error connecting to slave
An error occurred while trying to initialize the Modbus slave. This indicates that a collector setting hasn’t been configured correctly or that the Modbus server isn’t reachable during initialization.
Disconnected from slave
The Modbus client lost connection with the Modbus slave.