Merge pull request pymodbus-dev#355 from riptideio/pymodbus-dev#353-E…

…rror-Reading-Registers

pymodbus-dev#353 error reading registers

CHANGELOG.rst

@@ -1,3 +1,7 @@
+Version 2.1.1
+-----------------------------------------------------------
+* Provide an option to disable inter char timeouts with Modbus RTU.
+
 Version 2.1.0
 -----------------------------------------------------------
 * Fix Issues with Serial client where in partial data was read when the response size is unknown.

examples/common/synchronous_client.py

@@ -56,6 +56,12 @@ def run_sync_client():
     # * retries - Specify how many retries to allow per transaction (default=3)
     # * retry_on_empty - Is an empty response a retry (default = False)
     # * source_address - Specifies the TCP source address to bind to
+    # * strict - Applicable only for Modbus RTU clients.
+    #            Adheres to modbus protocol for timing restrictions
+    #            (default = True).
+    #            Setting this to False would disable the inter char timeout
+    #            restriction (t1.5) for Modbus RTU
+    #
     #
     # Here is an example of using these options::
     #

pymodbus/client/sync.py

@@ -415,6 +415,8 @@ def __init__(self, method='ascii', **kwargs):
         :param parity: Which kind of parity to use
         :param baudrate: The baud rate to use for the serial device
         :param timeout: The timeout between serial requests (default 3s)
+        :param strict:  Use Inter char timeout for baudrates <= 19200 (adhere
+        to modbus standards)
         """
         self.method = method
         self.socket = None
@@ -427,6 +429,7 @@ def __init__(self, method='ascii', **kwargs):
         self.parity = kwargs.get('parity',   Defaults.Parity)
         self.baudrate = kwargs.get('baudrate', Defaults.Baudrate)
         self.timeout = kwargs.get('timeout',  Defaults.Timeout)
+        self._strict = kwargs.get("strict", True)
         self.last_frame_end = None
         if self.method == "rtu":
             if self.baudrate > 19200:
@@ -473,7 +476,8 @@ def connect(self):
             _logger.error(msg)
             self.close()
         if self.method == "rtu":
-            self.socket.interCharTimeout = self.inter_char_timeout
+            if self._strict:
+                self.socket.interCharTimeout = self.inter_char_timeout
             self.last_frame_end = None
         return self.socket is not None
 

pymodbus/version.py

@@ -41,7 +41,7 @@ def __str__(self):
         return '[%s, version %s]' % (self.package, self.short())
 
 
-version = Version('pymodbus', 2, 1, 0)
+version = Version('pymodbus', 2, 1, 1)
 
 
 version.__name__ = 'pymodbus'  # fix epydoc error