QModbusRequest Class

QModbusRequest is a container class containing the function code and payload that is stored inside a Modbus ADU. 更多...

头：	#include <QModbusRequest>
CMake:	find_package(Qt6 REQUIRED COMPONENTS SerialBus) target_link_libraries(mytarget PRIVATE Qt6::SerialBus)
qmake:	QT += serialbus
继承：	QModbusPdu

• 所有成员列表，包括继承成员

公共类型

CalcFuncPtr

公共函数

	QModbusRequest ()
	QModbusRequest (const QModbusPdu & pdu )
	QModbusRequest (QModbusPdu::FunctionCode code , const QByteArray & data = QByteArray())
	QModbusRequest (QModbusPdu::FunctionCode code , Args... data )

静态公共成员

int	calculateDataSize (const QModbusRequest & request )
int	minimumDataSize (const QModbusRequest & request )
void	registerDataSizeCalculator (QModbusPdu::FunctionCode fc , QModbusRequest::CalcFuncPtr calculator )

相关非成员

QDataStream &

operator>> (QDataStream & stream , QModbusRequest & pdu )

详细描述

A Modbus request usually consists of a single byte describing the FunctionCode and N bytes of payload

A typical Modbus request can looks like this:

QModbusRequest request(QModbusRequest::WriteMultipleCoils,
    QByteArray::fromHex("0013000a02cd01"));
					

注意： When using the constructor taking the QByteArray , please make sure to convert the containing data to big-endian byte order before creating the request.

The same request can be created like this, if the values are known at compile time:

quint16 startAddress = 19, numberOfCoils = 10;
quint8 payloadInBytes = 2, outputHigh = 0xcd, outputLow = 0x01;
QModbusRequest request(QModbusRequest::WriteMultipleCoils, startAddress, numberOfCoils,
    payloadInBytes, outputHigh, outputLow);
					

成员类型文档编制

[alias] QModbusRequest:: CalcFuncPtr

Typedef for a pointer to a custom calculator function with the same signature as QModbusRequest::calculateDataSize .

成员函数文档编制

[constexpr noexcept] QModbusRequest:: QModbusRequest ()

Constructs an invalid QModbusRequest.

QModbusRequest:: QModbusRequest (const QModbusPdu & pdu )

构造副本为 pdu .

[explicit] QModbusRequest:: QModbusRequest ( QModbusPdu::FunctionCode code , const QByteArray & data = QByteArray())

构造 QModbusResponse with function code set to code and payload set to data . The data is expected to be stored in big-endian byte order already.

template <typename... Args> QModbusRequest:: QModbusRequest ( QModbusPdu::FunctionCode code , Args ... data )

Constructs a QModbusRequest with function code set to code and payload set to data . The data is converted and stored in big-endian byte order.

注意： Usage is limited quint8 and quint16 only. This is because QDataStream stream operators will not only append raw data, but also e.g. size, count, etc. for complex types.

[static] int QModbusRequest:: calculateDataSize (const QModbusRequest & request )

Calculates the expected data size for request based on the request's function code and data. Returns the full size of the request's data part; -1 if the size could not be properly calculated.

另请参阅 minimumDataSize and registerDataSizeCalculator .

[static] int QModbusRequest:: minimumDataSize (const QModbusRequest & request )

Returns the expected minimum data size for request based on the request's function code; -1 if the function code is not known.

[static] void QModbusRequest:: registerDataSizeCalculator ( QModbusPdu::FunctionCode fc , QModbusRequest::CalcFuncPtr calculator )

This function registers a user-defined implementation to calculate the request data size for function code fc . It can be used to extend or override the implementation inside QModbusRequest::calculateDataSize ().

The CalcFuncPtr is a typedef for a pointer to a custom calculator function with the following signature:

int myCalculateDataSize(const QModbusRequest &pdu);
					

相关非成员

QDataStream & operator>> ( QDataStream & stream , QModbusRequest & pdu )

读取 pdu 从 stream 并返回流引用。

注意： The function might fail to properly stream PDU's with function code QModbusPdu::Diagnostics or QModbusPdu::EncapsulatedInterfaceTransport because of the missing size indicator inside the PDU. In particular this may happen when the PDU is embedded into a stream that doesn't end with the diagnostic/encapsulated request itself.