Fix reconnectDelay to be within (100ms, 5min) (#1244)

* Fix broadCastEnable docstring
* Reduce min reconnect delay to 100ms, and cap max at 5 min.
Co-authored-by: jan Iversen <jancasacondor@gmail.com>

Author: alexrudd2

pymodbus/client/base.py

@@ -31,15 +31,17 @@ class ModbusBaseClient(ModbusClientMixin):
     :param close_comm_on_error: (optional) Close connection on error.
     :param strict: (optional) Strict timing, 1.5 character between requests.
     :param broadcast_enable: (optional) True to treat id 0 as broadcast address.
-    :param reconnect_delay: (optional) Delay in milliseconds before reconnecting.
+    :param reconnect_delay: (optional) Minimum delay in milliseconds before reconnecting.
+    :param reconnect_delay_max: (optional) Maximum delay in milliseconds before reconnecting.
     :param kwargs: (optional) Experimental parameters.
 
     .. tip::
         Common parameters and all external methods for all clients are documented here,
         and not repeated with each client.
 
     .. tip::
-        **reconnect_delay** doubles automatically with each unsuccessful connect.
+        **delay_ms** doubles automatically with each unsuccessful connect, from
+        **reconnect_delay** to **reconnect_delay_max**.
         Set `reconnect_delay=0` to avoid automatic reconnection.
 
     :mod:`ModbusBaseClient` is normally not referenced outside :mod:`pymodbus`,
@@ -82,6 +84,7 @@ class _params:  # pylint: disable=too-many-instance-attributes
         broadcast_enable: bool = None
         kwargs: dict = None
         reconnect_delay: int = None
+        reconnect_delay_max: int = None
 
         baudrate: int = None
         bytesize: int = None
@@ -107,6 +110,7 @@ def __init__(
         strict: bool = Defaults.Strict,
         broadcast_enable: bool = Defaults.BroadcastEnable,
         reconnect_delay: int = Defaults.ReconnectDelay,
+        reconnect_delay_max: int = Defaults.ReconnectDelayMax,
         **kwargs: any,
     ) -> None:
         """Initialize a client instance."""
@@ -118,7 +122,8 @@ def __init__(
         self.params.close_comm_on_error = bool(close_comm_on_error)
         self.params.strict = bool(strict)
         self.params.broadcast_enable = bool(broadcast_enable)
-        self.params.reconnect_delay = reconnect_delay
+        self.params.reconnect_delay = int(reconnect_delay)
+        self.params.reconnect_delay_max = int(reconnect_delay_max)
         self.params.kwargs = kwargs
 
         # Common variables.

pymodbus/client/tcp.py

@@ -89,6 +89,7 @@ def _create_protocol(self):
             strict=self.params.strict,
             broadcast_enable=self.params.broadcast_enable,
             reconnect_delay=self.params.reconnect_delay,
+            reconnect_delay_max=self.params.reconnect_delay_max,
             **self.params.kwargs,
         )
         protocol.factory = self
@@ -144,7 +145,7 @@ async def _reconnect(self):
         txt = f"Waiting {self.delay_ms} ms before next connection attempt."
         _logger.debug(txt)
         await asyncio.sleep(self.delay_ms / 1000)
-        self.delay_ms = 2 * self.delay_ms
+        self.delay_ms = min(2 * self.delay_ms, self.params.reconnect_delay_max)
 
         return await self._connect()
 

pymodbus/client/udp.py

@@ -109,6 +109,7 @@ def _create_protocol(self, host=None, port=0):
             strict=self.params.strict,
             broadcast_enable=self.params.broadcast_enable,
             reconnect_delay=self.params.reconnect_delay,
+            reconnect_delay_max=self.params.reconnect_delay_max,
             **self.params.kwargs,
         )
         protocol.params.host = host

pymodbus/constants.py

@@ -11,105 +11,120 @@
 class Defaults(Singleton):  # pylint: disable=too-few-public-methods
     """A collection of modbus default values.
 
-    .. attribute:: Port
+     .. attribute:: Port
 
-       The default modbus tcp server port (502)
+        The default modbus tcp server port (502)
 
-    .. attribute:: TLSPort
+     .. attribute:: TLSPort
 
-       The default modbus tcp over tls server port (802)
+        The default modbus tcp over tls server port (802)
 
 
-    .. attribute:: Backoff
+     .. attribute:: Backoff
 
-       The default exponential backoff delay (0.3 seconds)
+        The default exponential backoff delay (0.3 seconds) for a request
 
-    .. attribute:: Retries
+     .. attribute:: Retries
 
-       The default number of times a client should retry the given
-       request before failing (3)
+        The default number of times a client should retry the given
+        request before failing (3)
 
-    .. attribute:: RetryOnEmpty
+     .. attribute:: RetryOnEmpty
 
-       A flag indicating if a transaction should be retried in the
-       case that an empty response is received. This is useful for
-       slow clients that may need more time to process a request.
+        A flag indicating if a transaction should be retried in the
+        case that an empty response is received. This is useful for
+        slow clients that may need more time to process a request.
 
-    .. attribute:: RetryOnInvalid
+     .. attribute:: RetryOnInvalid
 
-       A flag indicating if a transaction should be retried in the
-       case that an invalid response is received.
+        A flag indicating if a transaction should be retried in the
+        case that an invalid response is received.
 
-    .. attribute:: Timeout
+     .. attribute:: Timeout
 
-       The default amount of time a client should wait for a request
-       to be processed (3 seconds)
+        The default amount of time a client should wait for a request
+        to be processed (3 seconds)
 
-    .. attribute:: Reconnects
+     .. attribute:: Reconnects
 
-       The default number of times a client should attempt to reconnect
-       before deciding the server is down (0)
+        The default number of times a client should attempt to reconnect
+        before deciding the server is down (0)
 
-    .. attribute:: TransactionId
+     .. attribute:: TransactionId
 
-       The starting transaction identifier number (0)
+        The starting transaction identifier number (0)
 
-    .. attribute:: ProtocolId
+     .. attribute:: ProtocolId
 
-       The modbus protocol id. Currently, this is set to 0 in all
-       but proprietary implementations.
+        The modbus protocol id. Currently, this is set to 0 in all
+        but proprietary implementations.
 
-    .. attribute:: Slave
+     .. attribute:: Slave
 
-       The modbus slave address. Currently, this is set to 0x00 which
-       means this request should be broadcast to all the slave devices
-       (really means that all the devices should respond).
+        The modbus slave address. Currently, this is set to 0x00 which
+        means this request should be broadcast to all the slave devices
+        (really means that all the devices should respond).
 
-    .. attribute:: Baudrate
+     .. attribute:: Baudrate
 
-       The speed at which the data is transmitted over the serial line.
-       This defaults to 19200.
+        The speed at which the data is transmitted over the serial line.
+        This defaults to 19200.
 
-    .. attribute:: Parity
+     .. attribute:: Parity
 
-       The type of checksum to use to verify data integrity. This can be
-       on of the following::
+        The type of checksum to use to verify data integrity. This can be
+        on of the following::
 
-         - (E)ven - 1 0 1 0 | P(0)
-         - (O)dd  - 1 0 1 0 | P(1)
-         - (N)one - 1 0 1 0 | no parity
+          - (E)ven - 1 0 1 0 | P(0)
+          - (O)dd  - 1 0 1 0 | P(1)
+          - (N)one - 1 0 1 0 | no parity
 
-       This defaults to (N)one.
+        This defaults to (N)one.
 
-    .. attribute:: Bytesize
+     .. attribute:: Bytesize
 
-       The number of bits in a byte of serial data.  This can be one of
-       5, 6, 7, or 8. This defaults to 8.
+        The number of bits in a byte of serial data.  This can be one of
+        5, 6, 7, or 8. This defaults to 8.
 
-    .. attribute:: Stopbits
+     .. attribute:: Stopbits
 
-       The number of bits sent after each character in a message to
-       indicate the end of the byte.  This defaults to 1.
+        The number of bits sent after each character in a message to
+        indicate the end of the byte.  This defaults to 1.
 
-    .. attribute:: ZeroMode
+     .. attribute:: ZeroMode
 
-       Indicates if the slave datastore should use indexing at 0 or 1.
-       More about this can be read in section 4.4 of the modbus specification.
+        Indicates if the slave datastore should use indexing at 0 or 1.
+        More about this can be read in section 4.4 of the modbus specification.
 
-    .. attribute:: IgnoreMissingSlaves
+     .. attribute:: IgnoreMissingSlaves
 
-       In case a request is made to a missing slave, this defines if an error
-       should be returned or simply ignored. This is useful for the case of a
-       serial server emulater where a request to a non-existent slave on a bus
-       will never respond. The client in this case will simply timeout.
+        In case a request is made to a missing slave, this defines if an error
+        should be returned or simply ignored. This is useful for the case of a
+        serial server emulater where a request to a non-existent slave on a bus
+        will never respond. The client in this case will simply timeout.
 
-    .. attribute:: broadcast_enable
+     .. attribute:: broadcastEnable
+
+       When False unit_id 0 will be treated as any other unit_id. When True and
+       the unit_id is 0 the server will execute all requests on all server
+       contexts and not respond and the client will skip trying to receive a
+       response. Default value False does not conform to Modbus spec but maintains
+       legacy behavior for existing pymodbus users.
+
+    .. attribute: reconnectDelayMin
+
+       When a connection has been dropped, the client will initially wait
+       reconnectDelayMin milliseconds before attempting a reconnect.  If the
+       attempt fails, it will double the delay before attempting again, up to a
+       a maximum of ReconnectDelayMax.  (binary exponential backoff).
+
+    .. attribute: reconnectDelayMax
+
+       When a connection has been dropped, the client will initially wait
+       reconnectDelayMin milliseconds before attempting a reconnect.  If the
+       attempt fails, it will double the delay before attempting again, up to a
+       a maximum of ReconnectDelayMax.  (binary exponential backoff)
 
-      When False unit_id 0 will be treated as any other unit_id. When True and
-      the unit_id is 0 the server will execute all requests on all server
-      contexts and not respond and the client will skip trying to receive a
-      response. Default value False does not conform to Modbus spec but maintains
-      legacy behavior for existing pymodbus users.
 
     """
 
@@ -136,7 +151,8 @@ class Defaults(Singleton):  # pylint: disable=too-few-public-methods
     IgnoreMissingSlaves = False
     ReadSize = 1024
     BroadcastEnable = False
-    ReconnectDelay = 1000 * 60 * 5
+    ReconnectDelay = 100
+    ReconnectDelayMax = 1000 * 60 * 5
     Count = 1
 
 

test/test_client.py

@@ -110,6 +110,7 @@ def test_client_mixin(arglist, method, arg, response):
                     "strict": not Defaults.Strict,
                     "broadcast_enable": not Defaults.BroadcastEnable,
                     "reconnect_delay": 117,
+                    "reconnect_delay_max": 250,
                 },
                 "defaults": {
                     "timeout": Defaults.Timeout,
@@ -119,6 +120,7 @@ def test_client_mixin(arglist, method, arg, response):
                     "strict": Defaults.Strict,
                     "broadcast_enable": Defaults.BroadcastEnable,
                     "reconnect_delay": Defaults.ReconnectDelay,
+                    "reconnect_delay_max": Defaults.ReconnectDelayMax,
                 },
             },
             "serial": {