diff --git a/goodwe/dt.py b/goodwe/dt.py
index 57e780a..b54e880 100644
--- a/goodwe/dt.py
+++ b/goodwe/dt.py
@@ -200,6 +200,7 @@ async def _read_setting(self, setting: Sensor) -> Any:
             if ex.message == ILLEGAL_DATA_ADDRESS:
                 logger.debug("Unsupported setting %s", setting.id_)
                 self._settings.pop(setting.id_, None)
+                raise ValueError(f'Unknown setting "{setting.id_}"')
             return None
 
     async def write_setting(self, setting_id: str, value: Any):
diff --git a/goodwe/es.py b/goodwe/es.py
index 096c4d5..3eed3d7 100644
--- a/goodwe/es.py
+++ b/goodwe/es.py
@@ -220,9 +220,11 @@ async def read_setting(self, setting_id: str) -> Any:
         elif setting_id.startswith("modbus"):
             response = await self._read_from_socket(self._read_command(int(setting_id[7:]), 1))
             return int.from_bytes(response.read(2), byteorder="big", signed=True)
-        else:
+        elif setting_id in self._settings:
             all_settings = await self.read_settings_data()
             return all_settings.get(setting_id)
+        else:
+            raise ValueError(f'Unknown setting "{setting_id}"')
 
     async def _read_setting(self, setting: Sensor) -> Any:
         count = (setting.size_ + (setting.size_ % 2)) // 2
diff --git a/goodwe/et.py b/goodwe/et.py
index 2ee1c6e..506ea01 100644
--- a/goodwe/et.py
+++ b/goodwe/et.py
@@ -628,6 +628,7 @@ async def _read_setting(self, setting: Sensor) -> Any:
             if ex.message == ILLEGAL_DATA_ADDRESS:
                 logger.debug("Unsupported setting %s", setting.id_)
                 self._settings.pop(setting.id_, None)
+                raise ValueError(f'Unknown setting "{setting.id_}"')
             return None
 
     async def write_setting(self, setting_id: str, value: Any):
diff --git a/tests/stability_check.py b/tests/stability_check.py
index cd09a2a..f1420eb 100644
--- a/tests/stability_check.py
+++ b/tests/stability_check.py
@@ -53,6 +53,21 @@ async def pymodbus(ip):
         i += 1
 
 
+async def read_modbus_range(ip, port, register, length):
+    inverter = await goodwe.connect(host=ip, port=port, family="ET", timeout=1, retries=3)
+    # inverter.set_keep_alive(False)
+
+    i = 1
+    while True:
+        logger.info("################################")
+        logger.info("          Request %d", i)
+        logger.info("################################")
+        await goodwe.protocol.ModbusRtuReadCommand(0xf7, register, length).execute(
+            goodwe.protocol.UdpInverterProtocol(ip, port, 1, 3))
+        await asyncio.sleep(5)
+        i += 1
+
+
 async def get_runtime_data(ip, port):
     inverter = await goodwe.connect(host=ip, port=port, family="ET", timeout=1, retries=3)
     # inverter.set_keep_alive(False)
@@ -68,4 +83,5 @@ async def get_runtime_data(ip, port):
 
 
 # asyncio.run(pymodbus('127.0.0.1'))
+# asyncio.run(read_modbus_range('192.168.2.14', 8899, 35100, 125))
 asyncio.run(get_runtime_data('127.0.0.1', 502))