#307 Fix partial data read for serial client when the response size is unknown

Author: dhoomakethu

.gitignore

@@ -36,4 +36,4 @@ test/__pycache__/
 /doc/html/
 /doc/_build/
 .pytest_cache/
-/.pymodhis
+**/.pymodhis

CHANGELOG.rst

@@ -1,8 +1,9 @@
 Version 2.0.2
 -----------------------------------------------------------
-* Fix Infinite sleep loop in RTU Framer
-* Add pygments as extra requirement for repl
-* More verbose logs for repl
+* Fix Issues with Serial client where in partial data was read when the response size is unknown.
+* Fix Infinite sleep loop in RTU Framer.
+* Add pygments as extra requirement for repl.
+* More verbose logs for repl.
 
 Version 2.0.1
 -----------------------------------------------------------

pymodbus/client/sync.py

@@ -512,15 +512,22 @@ def _send(self, request):
         return 0
 
     def _wait_for_data(self):
+        size = 0
+        more_data = False
         if self.timeout is not None and self.timeout != 0:
-            condition = partial(lambda start, timeout: (time.time() - start) <= timeout, timeout=self.timeout)
+            condition = partial(lambda start, timeout:
+                                (time.time() - start) <= timeout,
+                                timeout=self.timeout)
         else:
             condition = partial(lambda dummy1, dummy2: True, dummy2=None)
         start = time.time()
         while condition(start):
-            size = self._in_waiting()
-            if size:
+            avaialble = self._in_waiting()
+            if (more_data and not avaialble) or (more_data and avaialble == size):
                 break
+            if avaialble and avaialble != size:
+                more_data = True
+                size = avaialble
             time.sleep(0.01)
         return size
 

pymodbus/framer/rtu_framer.py

@@ -274,11 +274,6 @@ def sendPacket(self, message):
                     _logger.debug("Sleeping")
                     time.sleep(self.client.silent_interval)
         size = self.client.send(message)
-        # if size:
-        #     _logger.debug("Changing transaction state from 'SENDING' "
-        #                   "to 'WAITING FOR REPLY'")
-        #     self.client.state = ModbusTransactionState.WAITING_FOR_REPLY
-
         self.client.last_frame_end = round(time.time(), 6)
         return size