2nd try.

Author: janiversen

pymodbus/framer/rtu_framer.py

@@ -113,9 +113,9 @@ def resetFrame(self):
         end of the message (python just doesn't have the resolution to
         check for millisecond delays).
         """
-        # x = self._buffer
+        x = self._buffer
         super().resetFrame()
-        # self._buffer = x
+        self._buffer = x
 
     def isFrameReady(self):
         """Check if we should continue decode logic.
@@ -247,6 +247,7 @@ def sendPacket(self, message):
         :param message: Message to be sent over the bus
         :return:
         """
+        super().resetFrame()
         start = time.time()
         timeout = start + self.client.comm_params.timeout_connect
         while self.client.state != ModbusTransactionState.IDLE:

test/sub_client/test_client_faulty_response.py

@@ -5,7 +5,7 @@
 
 from pymodbus.exceptions import ModbusIOException
 from pymodbus.factory import ClientDecoder
-from pymodbus.framer import ModbusSocketFramer
+from pymodbus.framer import ModbusRtuFramer, ModbusSocketFramer
 
 
 class TestFaultyResponses:
@@ -30,6 +30,13 @@ def test_ok_frame(self, framer, callback):
         framer.processIncomingPacket(self.good_frame, callback, self.slaves)
         callback.assert_called_once()
 
+    def test_1917_frame(self, callback):
+        """Test invalid frame in issue 1917."""
+        recv = b"\x01\x86\x02\x00\x01"
+        framer = ModbusRtuFramer(ClientDecoder())
+        framer.processIncomingPacket(recv, callback, self.slaves)
+        callback.assert_not_called()
+
     def test_faulty_frame1(self, framer, callback):
         """Test ok frame."""
         faulty_frame = b"\x00\x04\x00\x00\x00\x05\x00\x03\x0a\x00\x04"