ModbusDevice

Description

The ModbusDevice object is the base class for Modbus client or server implementations. It provides basic communication mechanisms and properties and manages communication-related errors.

This object was introduced in InCore 2.0.

› Inherits:: Object
› Inherited by:: ModbusClient, ModbusRtuMaster, ModbusServer

Overview

Properties

activityLed
autoConnect
error
errorString
state
Object.objectId
Object.parent

Methods

Signals

connected()
disconnected()
errorOccurred()
Object.completed()

Properties

activityLed

This property holds an LED which to let blink on bus activity. Only supported for Modbus RTU.

This property was introduced in InCore 2.8.

› Type:: LED
› Signal:: activityLedChanged()
› Attributes:: Writable

autoConnect

This property holds whether the device should automatically reconnect if the connection is lost or closed.

› Type:: Boolean
› Default:: true
› Signal:: autoConnectChanged()
› Attributes:: Writable

error

This property holds the most recently occurred error or ModbusDevice.NoError if no error occurred. If the same error occurs multiple times this property does not change. Use the errorOccurred() signal to detect multiple occurrences of the same error.

› Type:: Error
› Signal:: errorChanged()
› Attributes:: Readonly

errorString

This property holds the current human readable error string corresponding to the current value in the error property. It may include additional information such as failure reasons or locations.

› Type:: String
› Signal:: errorStringChanged()
› Attributes:: Readonly

state

This property holds the current state of the Modbus device. See the State enumeration for details.

› Type:: State
› Default:: ModbusDevice.UnconnectedState
› Signal:: stateChanged()
› Attributes:: Readonly

Methods

connectDevice()

This method connects the device or master to the network. If autoConnect is true calling this function is not necessary.

› Returns:: Boolean

disconnectDevice()

This method disconnects the device or master from the network. Set autoConnect to false to make this function work properly.

Signals

connected()

This signal is emitted when the connection to the network is established.

disconnected()

This signal is emitted when the connection to the network is lost or closed.

errorOccurred()

This signal is emitted whenever an error has occurred, regardless of whether the error property has changed or not. In contrast to the change notification signal of the error property this signal is also emitted several times if a certain error occurs several times in succession.

Enumerations

BusInterface

This enumeration describes supported bus interface types used for Modbus RTU-based communication

This enumeration was introduced in InCore 2.8.

Name	Value	Description
`ModbusDevice.SerialPort`	`0`	use the serial port as specified in the portName property.
`ModbusDevice.BuiltinRS485`	`1`	use the builtin RS485 interface (availability depends on hardware type).
`ModbusDevice.BackplaneBus`	`2`	use the backplane bus interface (availability depends on hardware type).

Error

This enumeration describes all possible errors which can occur when connecting to or communicating with other Modbus devices.

Name	Value	Description
`ModbusDevice.NoError`	`0`	No error occurred or was detected.
`ModbusDevice.ReadError`	`1`	An error occurred during a read operation.
`ModbusDevice.WriteError`	`2`	An error occurred during a write operation.
`ModbusDevice.ConnectionError`	`3`	An error occurred when attempting to open the serial port or TCP connection.
`ModbusDevice.ConfigurationError`	`4`	An error occurred when attempting to set a configuration parameter.
`ModbusDevice.TimeoutError`	`5`	A timeout occurred during I/O. An I/O operation did not finish within a given time frame.
`ModbusDevice.ProtocolError`	`6`	A Modbus specific protocol error occurred.
`ModbusDevice.ReplyAbortedError`	`7`	The reply was aborted due to a disconnection of the device.
`ModbusDevice.UnknownError`	`8`	An unknown error occurred.
`ModbusDevice.BusOverloadError`	`9`	The bus is overloaded with requests or timeouts so at least one request has been dropped.

State

This enumeration describes all possible states of the Modbus device.

Name	Value	Description
`ModbusDevice.UnconnectedState`	`0`	The Modbus device is disconnected.
`ModbusDevice.ConnectingState`	`1`	The Modbus device is being connected.
`ModbusDevice.ConnectedState`	`2`	The Modbus device is connected.
`ModbusDevice.ClosingState`	`3`	The Modbus device is closing/shutting down.