QModbusRtuSerialServer Class

The QModbusRtuSerialServer class represents a Modbus server that uses a serial port for its communication with the Modbus client. More...

Header: #include <QModbusRtuSerialServer>
qmake: QT += serialbus
Since: Qt 6.2
Inherits: QModbusServer

Public Functions

QModbusRtuSerialServer(QObject *parent = nullptr)
virtual ~QModbusRtuSerialServer()
int interFrameDelay() const
void setInterFrameDelay(int microseconds)

Reimplemented Public Functions

virtual bool processesBroadcast() const override

Reimplemented Protected Functions

virtual void close() override
virtual bool open() override
virtual QModbusResponse processRequest(const QModbusPdu &request) override

Detailed Description

Communication via Modbus requires the interaction between a single Modbus client instance and multiple Modbus server. This class provides the Modbus server implementation via a serial port.

Since multiple Modbus server instances can interact with a Modbus client at the same time (using a serial bus), servers are identified by their serverAddress().

Member Function Documentation

QModbusRtuSerialServer::QModbusRtuSerialServer(QObject *parent = nullptr)

Constructs a QModbusRtuSerialServer with the specified parent. The serverAddress preset is 1.

[virtual] QModbusRtuSerialServer::~QModbusRtuSerialServer()

Destroys the QModbusRtuSerialServer instance.

[override virtual protected] void QModbusRtuSerialServer::close()

Reimplements: QModbusDevice::close().

[since 6.2] int QModbusRtuSerialServer::interFrameDelay() const

Returns the amount of microseconds for the silent interval between two consecutive Modbus messages.

This function was introduced in Qt 6.2.

See also setInterFrameDelay().

[override virtual protected] bool QModbusRtuSerialServer::open()

Reimplements: QModbusDevice::open().

Note: When calling this function, existing buffered data is removed from the serial port.

[override virtual protected] QModbusResponse QModbusRtuSerialServer::processRequest(const QModbusPdu &request)

Reimplements: QModbusServer::processRequest(const QModbusPdu &request).

Processes the Modbus client request specified by request and returns a Modbus response.

The Modbus function QModbusRequest::EncapsulatedInterfaceTransport with MEI Type 13 (0x0D) CANopen General Reference is filtered out because it is usually Modbus TCP or Modbus serial ASCII only.

A request to the RTU serial server will be answered with a Modbus exception response with the exception code QModbusExceptionResponse::IllegalFunction.

[override virtual] bool QModbusRtuSerialServer::processesBroadcast() const

Reimplements: QModbusServer::processesBroadcast() const.

[since 6.2] void QModbusRtuSerialServer::setInterFrameDelay(int microseconds)

Sets the amount of microseconds for the silent interval between two consecutive Modbus messages. By default, the class implementation will use a pre-calculated value according to the Modbus specification. A active or running connection is not affected by such delay changes.

Note: If microseconds is set to -1 or microseconds is less than the pre-calculated delay then this pre-calculated value is used as frame delay.

This function was introduced in Qt 6.2.

See also interFrameDelay().

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