Merge pull request #491 from Pho3niX90/bugfix/interframe-fix

Enforce Solis-Compliant 310ms Modbus Inter-Frame Spacing

Author: Pho3niX90

custom_components/solis_modbus/client_manager.py

@@ -8,6 +8,12 @@
 
 _LOGGER = logging.getLogger(__name__)
 
+# Solis RS485_MODBUS protocol (Hybrid Inverter V3.1 / PV Grid-Connected Inverter V19),
+# section 3.2 "Inter-frame interval requirement": "More than 300ms communications frame
+# interval is required." Applies to every request on the link, read or write. 310ms gives
+# a small margin above the documented floor (see issue #480).
+MIN_INTER_FRAME_MS = 310
+
 
 class ModbusClientManager:
     _instance = None
@@ -102,7 +108,7 @@ async def inter_frame_wait(self, connection_id: str, is_write: bool = False) ->
         """Minimum spacing between Modbus operations on one TCP/serial link, across all controllers sharing it."""
         if connection_id not in self._clients:
             return
-        delay_ms = 100 if is_write else 50
+        delay_ms = MIN_INTER_FRAME_MS
         entry = self._clients[connection_id]
         current_time = time.perf_counter()
         last = float(entry.get("last_modbus_request", 0.0))

tests/test_client_manager.py

@@ -1,8 +1,8 @@
 import unittest
 from unittest import IsolatedAsyncioTestCase
-from unittest.mock import MagicMock, patch
+from unittest.mock import AsyncMock, MagicMock, patch
 
-from custom_components.solis_modbus.client_manager import ModbusClientManager
+from custom_components.solis_modbus.client_manager import MIN_INTER_FRAME_MS, ModbusClientManager
 
 
 class TestModbusClientManager(unittest.TestCase):
@@ -91,6 +91,27 @@ async def test_inter_frame_wait_updates_shared_timestamp(self, mock_client_cls):
         await self.manager.inter_frame_wait("1.2.3.4:502", is_write=False)
         self.assertGreater(self.manager.get_last_modbus_request("1.2.3.4:502"), 0.0)
 
+    @patch("custom_components.solis_modbus.client_manager.AsyncModbusTcpClient")
+    @patch("custom_components.solis_modbus.client_manager.time.perf_counter")
+    @patch("custom_components.solis_modbus.client_manager.asyncio.sleep", new_callable=AsyncMock)
+    async def test_inter_frame_wait_enforces_min_interval_for_reads_and_writes(self, mock_sleep, mock_perf_counter, mock_client_cls):
+        mock_client_cls.return_value = MagicMock()
+        # Two operations back-to-back on the same connection: each should independently
+        # compute a wait based on MIN_INTER_FRAME_MS, regardless of is_write.
+        # Call sequence: [read: current_time, read: recorded last] [write: current_time, write: recorded last]
+        mock_perf_counter.side_effect = [0.0, 0.31, 0.32, 0.62]
+        self.manager.get_tcp_client("1.2.3.4", 502)
+
+        await self.manager.inter_frame_wait("1.2.3.4:502", is_write=False)
+        await self.manager.inter_frame_wait("1.2.3.4:502", is_write=True)
+
+        expected_delay_s = MIN_INTER_FRAME_MS / 1000
+        self.assertEqual(2, mock_sleep.call_count)
+        # Read: 0.0 elapsed since last (0.0) -> full MIN_INTER_FRAME_MS wait.
+        self.assertAlmostEqual(expected_delay_s, mock_sleep.call_args_list[0].args[0])
+        # Write: 10ms elapsed since last (0.31) -> remaining wait is MIN_INTER_FRAME_MS - 10ms.
+        self.assertAlmostEqual(expected_delay_s - 0.01, mock_sleep.call_args_list[1].args[0])
+
 
 if __name__ == "__main__":
     unittest.main()