fix: Validate that the queried number of registers matches the number…

… of registers received

Sometimes we get a response with almost all values being 0, usually also multiple registers are missing. In that case we just return an empty dictionary. This validation is not perfect but it should be good enough for now.

app/app.py

@@ -328,13 +328,15 @@ def query_modbus(self):
         registers = {}
         current_register = self.register_span_start
         chunk_size = self.config["datalogger"]["register_chunks"]
+        queried_registers_counter = 0
 
         # Loop while we still have registers to query
         while current_register < self.register_span_end:
             try:
                 logging.info(
                     f"Querying register {current_register} to {current_register + chunk_size}"
                 )
+                queried_registers_counter += chunk_size
 
                 message = client.read_input_registers(
                     slave=self.config["datalogger"]["slave_id"],
@@ -368,6 +370,13 @@ def query_modbus(self):
 
         client.close()
 
+        # Sometimes we get a response with almost all values being 0, usually also multiple registers
+        # are missing. In that case we just return an empty dictionary. This validation is not perfect
+        # but it should be good enough for now.
+        if len(registers) != queried_registers_counter:
+            logging.info(f"Validation of number of queried registers failed. Queried: {len(registers)}, received: {queried_registers_counter}")
+            return {}
+
         return registers
 
     def pick_from_registers(self, registers, start, count):