fix error calculating response pdu length for read coil/discrete input requests

pymodbus/bit_read_message.py

@@ -15,6 +15,7 @@ class ReadBitsRequestBase(ModbusRequest):
     ''' Base class for Messages Requesting bit values '''
 
     _rtu_frame_size = 8
+
     def __init__(self, address, count, **kwargs):
         ''' Initializes the read request data
 
@@ -41,10 +42,15 @@ def decode(self, data):
 
     def get_response_pdu_size(self):
         """
-        Func_code (1 byte) + Byte Count(1 byte) + Quantity of Coils (n Bytes)
+        Func_code (1 byte) + Byte Count(1 byte) + Quantity of Coils (n Bytes)/8,
+        if the remainder is different of 0 then N = N+1
         :return: 
         """
-        return 1 + 1 + self.count
+        count = self.count//8
+        if self.count % 8:
+            count += 1
+
+        return 1 + 1 + count
 
     def __str__(self):
         ''' Returns a string representation of the instance

pymodbus/transaction.py

@@ -88,7 +88,10 @@ def execute(self, request):
         while retries > 0:
             try:
                 self.client.connect()
-                self.client._send(self.client.framer.buildPacket(request))
+                packet = self.client.framer.buildPacket(request)
+                if _logger.isEnabledFor(logging.DEBUG):
+                    _logger.debug("send: " + " ".join([hex(byte2int(x)) for x in packet]))
+                self.client._send(packet)
                 result = self.client._recv(expected_response_length)
 
                 if not result and self.retry_on_empty:

test/test_bit_read_messages.py

@@ -17,7 +17,8 @@
 from pymodbus.compat import iteritems
 
 from .modbus_mocks import MockContext
-
+res = [True] * 21
+res.extend([False] * 3)
 #---------------------------------------------------------------------------#
 # Fixture
 #---------------------------------------------------------------------------#
@@ -78,7 +79,7 @@ def testBitReadBaseRequests(self):
         ''' Test bit read request encoding '''
         messages = {
             ReadBitsRequestBase(12, 14)        : b'\x00\x0c\x00\x0e',
-            ReadBitsResponseBase([1,0,1,1,0])  : b'\x01\x0d',
+            ReadBitsResponseBase([1,0,1,1,0])  : b'\x01\x0d'
         }
         for request, expected in iteritems(messages):
             self.assertEqual(request.encode(), expected)
@@ -118,6 +119,20 @@ def testBitReadMessageExecuteSuccess(self):
             result = request.execute(context)
             self.assertEqual(result.bits, [True] * 5)
 
+    def testBitReadMessageGetResponsePDU(self):
+        requests = {
+            ReadCoilsRequest(1,5): 3,
+            ReadCoilsRequest(1, 8): 3,
+            ReadCoilsRequest(0, 16): 4,
+            ReadDiscreteInputsRequest(1, 21): 5,
+            ReadDiscreteInputsRequest(1, 24): 5,
+            ReadDiscreteInputsRequest(1, 1900): 240,
+        }
+        for request, expected in iteritems(requests):
+            pdu_len = request.get_response_pdu_size()
+            self.assertEqual(pdu_len, expected)
+
+
 #---------------------------------------------------------------------------#
 # Main
 #---------------------------------------------------------------------------#

test/test_bit_write_messages.py

@@ -46,6 +46,14 @@ def testBitWriteBaseRequests(self):
         for request, expected in iteritems(messages):
             self.assertEqual(request.encode(), expected)
 
+    def testBitWriteMessageGetResponsePDU(self):
+        requests = {
+            WriteSingleCoilRequest(1, 0xabcd): 5
+        }
+        for request, expected in iteritems(requests):
+            pdu_len = request.get_response_pdu_size()
+            self.assertEqual(pdu_len, expected)
+
     def testWriteMultipleCoilsRequest(self):
         request = WriteMultipleCoilsRequest(1, [True]*5)
         request.decode(b'\x00\x01\x00\x05\x01\x1f')