add 'change_rate' randomization option (#1229)

* add 'change_rate' randomization option

Author: Chris Hung

pymodbus/repl/server/main.py

@@ -166,6 +166,13 @@ def run(
         help="Randomize every `r` reads. 0=never, 1=always,2=every-second-read"
         ", and so on. Applicable IR and DI.",
     ),
+    change_rate: int = typer.Option(
+        0,
+        "--change-rate",
+        "-c",
+        help="Rate in % registers to change. 0=none, 100=all, 12=12% of registers"
+        ", and so on. Applicable IR and DI.",
+    ),
 ):
     """Run Reactive Modbus server.
 
@@ -195,6 +202,7 @@ def run(
 
     modbus_config["handler"] = handler
     modbus_config["randomize"] = randomize
+    modbus_config["change_rate"] = change_rate
     app = ReactiveServer.factory(
         modbus_server,
         framer,

pymodbus/server/reactive/main.py

@@ -113,6 +113,7 @@ def __init__(
         holding_registers: BaseModbusDataBlock = None,
         zero_mode: bool = False,
         randomize: int = 0,
+        change_rate: int = 0,
         **kwargs,
     ):
         """Reactive Modbus slave context supporting simulating data.
@@ -124,6 +125,8 @@ def __init__(
         :param zero_mode: Enable zero mode for data blocks
         :param randomize: Randomize reads every <n> reads for DI and IR,
                           default is disabled (0)
+        :param change_rate: Rate in % of registers to change for DI and IR,
+                          default is disabled (0)
         :param min_binary_value: Minimum value for coils and discrete inputs
         :param max_binary_value: Max value for discrete inputs
         :param min_register_value: Minimum value for input registers
@@ -142,6 +145,9 @@ def __init__(
         min_register_value = kwargs.get("min_register_value", 0)
         max_register_value = kwargs.get("max_register_value", 65535)
         self._randomize = randomize
+        self._change_rate = change_rate
+        if self._randomize > 0:
+            self._change_rate = 0
         self._lock = threading.Lock()
         self._read_counter = {"d": 0, "i": 0}
         self._min_binary_value = min_binary_value
@@ -177,6 +183,21 @@ def getValues(self, fc_as_hex, address, count=1):
                     #              "'%s'", _block_type, values, address)
                     self.store[_block_type].setValues(address, values)
                 self._read_counter[_block_type] += 1
+        elif self._change_rate > 0 and _block_type in {"d", "i"}:
+            regs_to_changes = round(count * self._change_rate / 100)
+            random_indices = random.sample(range(count), regs_to_changes)
+            for offset in random_indices:
+                with self._lock:
+                    # Update values
+                    if _block_type == "d":
+                        min_val = self._min_binary_value
+                        max_val = self._max_binary_value
+                    else:
+                        min_val = self._min_register_value
+                        max_val = self._max_register_value
+                    self.store[_block_type].setValues(
+                        address + offset, random.randint(min_val, max_val)
+                    )
         values = self.store[_block_type].getValues(address, count)
         return values
 
@@ -385,13 +406,15 @@ def create_context(
         unit: list[int] = [1],
         single: bool = False,
         randomize: int = 0,
+        change_rate: int = 0,
     ):  # pylint: disable=dangerous-default-value
         """Create Modbus context.
 
         :param data_block_settings: Datablock (dict) Refer DEFAULT_DATA_BLOCK
         :param unit: Unit id for the slave
         :param single: To run as a single slave
         :param randomize: Randomize every <n> reads for DI and IR.
+        :param change_rate: Rate in % of registers to change for DI and IR.
         :return: ModbusServerContext object
         """
         data_block = data_block_settings.pop("data_block", DEFAULT_DATA_BLOCK)
@@ -422,7 +445,11 @@ def create_context(
                     block[modbus_entity] = db(start_address, default_values)
 
             slave_context = ReactiveModbusSlaveContext(
-                **block, randomize=randomize, zero_mode=True, **data_block_settings
+                **block,
+                randomize=randomize,
+                change_rate=change_rate,
+                zero_mode=True,
+                **data_block_settings,
             )
             if not single:
                 slaves[i] = slave_context
@@ -471,6 +498,7 @@ def factory(  # pylint: disable=dangerous-default-value,too-many-arguments
             sys.exit(1)
         server = SERVER_MAPPER.get(server)
         randomize = kwargs.pop("randomize", 0)
+        change_rate = kwargs.pop("change_rate", 0)
         if not framer:
             framer = DEFAULT_FRAMER.get(server)
         if not context:
@@ -479,6 +507,7 @@ def factory(  # pylint: disable=dangerous-default-value,too-many-arguments
                 unit=unit,
                 single=single,
                 randomize=randomize,
+                change_rate=change_rate,
             )
         if not identity:
             identity = cls.create_identity()