The QModbusClient class is the interface to send Modbus requests. 更多...
| 头： | #include <QModbusClient> |
| qmake: | QT += serialbus |
| Since: | Qt 5.8 |
| 继承： | QModbusDevice |
| 继承者： |
该类在 Qt 5.8 引入。
| QModbusClient (QObject * parent = nullptr) | |
| int | numberOfRetries () const |
| QModbusReply * | sendRawRequest (const QModbusRequest & request , int serverAddress ) |
| QModbusReply * | sendReadRequest (const QModbusDataUnit & read , int serverAddress ) |
| QModbusReply * | sendReadWriteRequest (const QModbusDataUnit & read , const QModbusDataUnit & write , int serverAddress ) |
| QModbusReply * | sendWriteRequest (const QModbusDataUnit & write , int serverAddress ) |
| void | setNumberOfRetries (int number ) |
| void | setTimeout (int newTimeout ) |
| int | timeout () const |
| void | timeoutChanged (int newTimeout ) |
| virtual bool | processPrivateResponse (const QModbusResponse & response , QModbusDataUnit * data ) |
| virtual bool | processResponse (const QModbusResponse & response , QModbusDataUnit * data ) |
The QModbusClient API is constructed around one QModbusClient object, which holds the common configuration and settings for the requests it sends. One QModbusClient should be enough for the whole Qt application.
Once a QModbusClient object has been created, the application can use it to send requests. The returned object is used to obtain any data returned in response to the corresponding request.
QModbusClient has an asynchronous API. When the finished slot is called, the parameter it takes is the QModbusReply object containing the PDU as well as meta-data (Addressing, etc.).
Note: QModbusClient queues the requests it receives. The number of requests executed in parallel is dependent on the protocol. For example, the HTTP protocol on desktop platforms issues 6 requests in parallel for one host/port combination.
This property holds the timeout value used by this client
Returns the timeout value used by this QModbusClient instance in ms. A timeout is indicated by a TimeoutError . The default value is 1000 ms.
访问函数：
| int | timeout () const |
| void | setTimeout (int newTimeout ) |
通知程序信号：
| void | timeoutChanged (int newTimeout ) |
另请参阅 setTimeout .
Constructs a Modbus client device with the specified parent .
[signal]
void
QModbusClient::
timeoutChanged
(
int
newTimeout
)
This signal is emitted when the timeout used by this QModbusClient instance is changed. The new response timeout for the device is passed as newTimeout .
注意： 通知程序信号对于特性 timeout .
另请参阅 setTimeout ().
Returns the number of retries a client will perform before a request fails. The default value is set to
3
.
另请参阅 setNumberOfRetries ().
[virtual protected]
bool
QModbusClient::
processPrivateResponse
(const
QModbusResponse
&
response
,
QModbusDataUnit
*
data
)
To be implemented by custom Modbus client implementation. The default implementation ignores response and data . It always returns false to indicate error.
[virtual protected]
bool
QModbusClient::
processResponse
(const
QModbusResponse
&
response
,
QModbusDataUnit
*
data
)
Processes a Modbus server
response
and stores the decoded information in
data
。返回
true
当成功时；否则
false
.
注意： The default implementation does not support all FunctionCode s. Override this method in a custom Modbus client implementations to handle the needed functions.
Sends a raw Modbus request . A raw request can contain anything that fits inside the Modbus PDU data section and has a valid function code. The only check performed before sending is therefore the validity check, see QModbusPdu::isValid . If no error occurred the function returns a a new valid QModbusReply ; nullptr otherwise. Modbus networks may have multiple servers, each server has a unique serverAddress .
另请参阅 QModbusReply::rawResult ().
Sends a request to read the contents of the data pointed by read . Returns a new valid QModbusReply object if no error occurred, otherwise nullptr. Modbus network may have multiple servers, each server has unique serverAddress .
Sends a request to read the contents of the data pointed by read and to modify the contents of the data pointed by write using Modbus function code QModbusPdu::ReadWriteMultipleRegisters . Returns a new valid QModbusReply object if no error occurred, otherwise nullptr. Modbus network may have multiple servers, each server has unique serverAddress .
注意： : Sending this kind of request is only valid of both read and write are of type QModbusDataUnit::HoldingRegisters .
Sends a request to modify the contents of the data pointed by write . Returns a new valid QModbusReply object if no error occurred, otherwise nullptr. Modbus network may have multiple servers, each server has unique serverAddress .
设置
number
of retries a client will perform before a request fails. The default value is set to
3
.
注意：
The new value must be greater than or equal to
0
. Changing this property will only effect new requests, not already scheduled ones.
另请参阅 numberOfRetries ().
设置 newTimeout for this QModbusClient instance. The minimum timeout is 10 ms.
The timeout is used by the client to determine how long it waits for a response from the server. If the response is not received within the required timeout, the TimeoutError 有设置。
Already active/running timeouts are not affected by such timeout duration changes.
注意： setter 函数对于特性 timeout .
另请参阅 timeout and timeoutChanged ().