Patch: Extended timeout handling in ModbusTransactionManager

pymodbus/client/sync.py

@@ -303,6 +303,9 @@ 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)
+
+        # Set a relatively fast timeout on self.socket.
+        self.socket_poll_rate = min(0.1, self.timeout)  
 
     @staticmethod
     def __implementation(method):
@@ -325,9 +328,10 @@ def connect(self):
         '''
         if self.socket: return True
         try:
-            self.socket = serial.Serial(port=self.port, timeout=self.timeout,
-                bytesize=self.bytesize, stopbits=self.stopbits,
-                baudrate=self.baudrate, parity=self.parity)
+            self.socket = serial.Serial(port=self.port, 
+                timeout=self.socket_poll_rate, bytesize=self.bytesize, 
+                stopbits=self.stopbits, baudrate=self.baudrate, 
+                parity=self.parity)
         except serial.SerialException, msg:
             _logger.error(msg)
             self.close()

pymodbus/transaction.py

@@ -4,9 +4,10 @@
 import sys
 import struct
 import socket
+import time
 from binascii import b2a_hex, a2b_hex
 
-from pymodbus.exceptions import ModbusIOException
+from pymodbus.exceptions import ModbusIOException, NotImplementedException
 from pymodbus.constants  import Defaults
 from pymodbus.interfaces import IModbusFramer
 from pymodbus.utilities  import checkCRC, computeCRC
@@ -58,21 +59,27 @@ def execute(self, request):
         request.transaction_id = self.getNextTID()
         _logger.debug("Running transaction %d" % request.transaction_id)
 
+
         while retries > 0:
+            start_time = time.time()
             try:
                 self.client.connect()
                 self.client._send(self.client.framer.buildPacket(request))
                 # I need to fix this to read the header and the result size,
                 # as this may not read the full result set, but right now
                 # it should be fine...
-                result = self.client._recv(1024)
+                result = ''
+                while result == '' and time.time() < start_time + self.client.timeout:
+                    # Keep retrying until timeout elapses
+                    result = self.client._recv(1024)
                 if not result and self.retry_on_empty:
+                    _logger.debug("No data received within timeout. Querying again")
                     retries -= 1
                     continue
                 if _logger.isEnabledFor(logging.DEBUG):
                     _logger.debug("recv: " + " ".join([hex(ord(x)) for x in result]))
                 self.client.framer.processIncomingPacket(result, self.addTransaction)
-                break;
+                break
             except socket.error, msg:
                 self.client.close()
                 _logger.debug("Transaction failed. (%s) " % msg)