feat: Restore protocol client integration for Modbus in signals endpoint

- Use real Modbus data when available
- Keep fallback for OPC UA until security policy issues are resolved
- Maintain graceful fallback to mock data if protocol clients fail

src/dashboard/api.py

@@ -716,12 +716,98 @@ async def get_signals():
     
     signals = []
     
-    # Always use fallback signals for now to avoid protocol client issues
-    logger.info("using_fallback_signals_for_testing")
-    for station_id, station in stations.items():
-        pumps = pumps_by_station.get(station_id, [])
-        for pump in pumps:
-            signals.extend(_create_fallback_signals(station_id, pump['pump_id']))
+    # Try to use real protocol data for Modbus, fallback for OPC UA
+    try:
+        from .protocol_clients import ModbusTCPClient
+        
+        # Create Modbus client
+        modbus_client = ModbusTCPClient(
+            host="localhost",
+            port=502,
+            unit_id=1
+        )
+        
+        # Connect to Modbus server
+        if await modbus_client.connect():
+            logger.info("using_real_modbus_data")
+            
+            # Read pump data from Modbus server
+            for station_id, station in stations.items():
+                pumps = pumps_by_station.get(station_id, [])
+                for pump in pumps:
+                    pump_id = pump['pump_id']
+                    
+                    # Get pump data from Modbus
+                    pump_data = await modbus_client.get_pump_data(pump_id)
+                    
+                    # Create signals from real Modbus data
+                    signals.extend([
+                        {
+                            "name": f"Station_{station_id}_Pump_{pump_id}_Setpoint",
+                            "protocol": "modbus",
+                            "address": "0",
+                            "data_type": "Integer",
+                            "current_value": f"{pump_data.get('setpoint', 0)} Hz",
+                            "quality": "Good",
+                            "timestamp": datetime.now().strftime("%Y-%m-%d %H:%M:%S")
+                        },
+                        {
+                            "name": f"Station_{station_id}_Pump_{pump_id}_ActualSpeed",
+                            "protocol": "modbus",
+                            "address": "100",
+                            "data_type": "Integer",
+                            "current_value": f"{pump_data.get('actual_speed', 0)} Hz",
+                            "quality": "Good",
+                            "timestamp": datetime.now().strftime("%Y-%m-%d %H:%M:%S")
+                        },
+                        {
+                            "name": f"Station_{station_id}_Pump_{pump_id}_Power",
+                            "protocol": "modbus",
+                            "address": "200",
+                            "data_type": "Integer",
+                            "current_value": f"{pump_data.get('power', 0)} kW",
+                            "quality": "Good",
+                            "timestamp": datetime.now().strftime("%Y-%m-%d %H:%M:%S")
+                        },
+                        {
+                            "name": f"Station_{station_id}_Pump_{pump_id}_FlowRate",
+                            "protocol": "modbus",
+                            "address": "300",
+                            "data_type": "Integer",
+                            "current_value": f"{pump_data.get('flow_rate', 0)} m³/h",
+                            "quality": "Good",
+                            "timestamp": datetime.now().strftime("%Y-%m-%d %H:%M:%S")
+                        },
+                        {
+                            "name": f"Station_{station_id}_Pump_{pump_id}_SafetyStatus",
+                            "protocol": "modbus",
+                            "address": "400",
+                            "data_type": "Integer",
+                            "current_value": f"{pump_data.get('safety_status', 0)}",
+                            "quality": "Good",
+                            "timestamp": datetime.now().strftime("%Y-%m-%d %H:%M:%S")
+                        }
+                    ])
+                    
+                    # Add OPC UA fallback signals
+                    signals.extend(_create_fallback_signals(station_id, pump_id))
+            
+            await modbus_client.disconnect()
+        else:
+            logger.warning("modbus_connection_failed_using_fallback")
+            # Fallback to mock data if Modbus connection fails
+            for station_id, station in stations.items():
+                pumps = pumps_by_station.get(station_id, [])
+                for pump in pumps:
+                    signals.extend(_create_fallback_signals(station_id, pump['pump_id']))
+                    
+    except Exception as e:
+        logger.error(f"error_using_real_protocol_data_using_fallback", error=str(e))
+        # Fallback to mock data if any error occurs
+        for station_id, station in stations.items():
+            pumps = pumps_by_station.get(station_id, [])
+            for pump in pumps:
+                signals.extend(_create_fallback_signals(station_id, pump['pump_id']))
     
     # Add system status signals
     signals.extend([