Fix NEXA and NOAH 0x0103 holding register dump parsing crash

Author: robertzaage

CHANGELOG.md

@@ -1,3 +1,8 @@
+## v2.7.3
+
+### Bug Fixes
++ Fixed NEXA and NOAH devices crashing the parser every hour when sending holding register dumps (message type 0x0103). These messages are now properly decoded and their sensor values are published to Home Assistant (#198)
+
 ## v2.7.2
 
 ### New Features

grobro/grobro/client.py

@@ -20,6 +20,7 @@
 from grobro.grobro.builder import append_crc
 from grobro.grobro.builder import scramble
 from grobro.model.modbus_function import GrowattModbusFunctionSingle
+from grobro.model.modbus_message import GrowattModbusBlock
 from grobro.model.modbus_message import GrowattModbusFunction
 from grobro.model.modbus_message import GrowattModbusMessage
 from grobro.model.mqtt_config import MQTTConfig
@@ -367,17 +368,35 @@ def __on_message(self, client, userdata, msg: MQTTMessage):
                 self._client.publish(topic, eco["data"], retain=PUBLISH_SENSORS_RETAINED)
                 return
 
+            modbus_message = None
+
             # NOAH-specific message types (FE19 config, 0103 holding regs, etc.)
             noah_msg = parser.parse_noah_message(unscrambled)
-            if noah_msg and noah_msg.get("message_type") == 0xFE19 and device_id.startswith("0PVP"):
-                config = noah_msg.get("config")
-                if config and config.serial_number:
-                    LOG.info("Received NOAH config for %s (sw_version=%s)", config.serial_number, config.sw_version or "?")
-                    self.on_config(device_id, config)
-                    return
+            if noah_msg:
+                if noah_msg.get("message_type") == 0xFE19 and device_id.startswith("0PVP"):
+                    config = noah_msg.get("config")
+                    if config and config.serial_number:
+                        LOG.info("Received NOAH config for %s (sw_version=%s)", config.serial_number, config.sw_version or "?")
+                        self.on_config(device_id, config)
+                        return
+
+                if noah_msg.get("message_type") == 0x0103:
+                    registers = noah_msg.get("registers", [])
+                    if registers:
+                        block = GrowattModbusBlock(
+                            start=0,
+                            end=len(registers) - 1,
+                            values=b"".join(struct.pack(">H", v) for v in registers),
+                        )
+                        modbus_message = GrowattModbusMessage(
+                            unknown=0,
+                            device_id=noah_msg["device_id"],
+                            function=GrowattModbusFunction.READ_SINGLE_REGISTER,
+                            register_blocks=[block],
+                        )
 
-            # Generic modbus message
-            modbus_message = GrowattModbusMessage.parse_grobro(unscrambled)
+            if modbus_message is None:
+                modbus_message = GrowattModbusMessage.parse_grobro(unscrambled)
             LOG.debug("Received modbus message: %s", modbus_message)
 
             if modbus_message:

grobro/model/modbus_message.py

@@ -169,6 +169,9 @@ def parse_grobro(buffer) -> Optional["GrowattModbusMessage"]:
 
             while len(buffer) > offset + 6:
                 block = GrowattModbusBlock.parse_grobro(buffer[offset:])
+                if block is None:
+                    LOG.warning("Failed to parse modbus block at offset %d", offset)
+                    break
                 register_blocks.append(block)
                 offset += block.size()