QModbusDevice: introduce an InvalidResponseError error code

[ChangeLog][QModbusDevice] Introduce a new InvalidResponseError error
code. Use this code instead of UnknownError when QModbusClient fails to
parse the response.

Task-number: QTBUG-103879
Pick-to: 6.4
Change-Id: Ie4bd1d3c988590a851062a553103733e4a0f5d1c
Reviewed-by: Sze Howe Koh <szehowe.koh@gmail.com>
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>

3 files changed, 11 insertions, 9 deletions

diff --git a/src/serialbus/qmodbusclient.cpp b/src/serialbus/qmodbusclient.cpp
index 6f1335e..eca713c 100644
--- a/src/serialbus/qmodbusclient.cpp
+++ b/src/serialbus/qmodbusclient.cpp
@@ -336,7 +336,7 @@ void QModbusClientPrivate::processQueueElement(const QModbusResponse &pdu,
 
     QModbusDataUnit unit = element.unit;
     if (!q_func()->processResponse(pdu, &unit)) {
-        element.reply->setError(QModbusDevice::UnknownError,
+        element.reply->setError(QModbusDevice::InvalidResponseError,
             QModbusClient::tr("An invalid response has been received."));
         return;
     }
diff --git a/src/serialbus/qmodbusdevice.cpp b/src/serialbus/qmodbusdevice.cpp
index e7b891f..d43f3b3 100644
--- a/src/serialbus/qmodbusdevice.cpp
+++ b/src/serialbus/qmodbusdevice.cpp
@@ -166,13 +166,14 @@ void QModbusDevice::setConnectionParameter(ConnectionParameter parameter, const
     \value ReplyAbortedError    The reply was aborted due to a disconnection of
                                 the device.
     \value UnknownError         An unknown error occurred.
-
-    \note An UnknownError can also indicate that the received
-    \l {QModbusPdu::}{FunctionCode} is not supported in the current
-    implementation. In this case custom Modbus client implementations need to
-    override the \l {QModbusClient::}{processResponse()} and
-    \l {QModbusClient::}{processPrivateResponse()} methods to provide support
-    for needed functions.
+    \value [since 6.4] InvalidResponseError An error occurred while parsing the
+                                response, or the \l {QModbusPdu::}{FunctionCode}
+                                is not supported by the current implementation.
+                                In the latter case custom Modbus client
+                                implementation can override the
+                                \l {QModbusClient::}{processResponse()} and
+                                \l {QModbusClient::}{processPrivateResponse()}
+                                methods to provide support for needed functions.
 */
 
 /*!
diff --git a/src/serialbus/qmodbusdevice.h b/src/serialbus/qmodbusdevice.h
index e10555e..878e3db 100644
--- a/src/serialbus/qmodbusdevice.h
+++ b/src/serialbus/qmodbusdevice.h
@@ -26,7 +26,8 @@ public:
         TimeoutError,
         ProtocolError,
         ReplyAbortedError,
-        UnknownError
+        UnknownError,
+        InvalidResponseError
     };
     Q_ENUM(Error)