Allow response transaction_id 0. (#2844)

janiversen · web-flow · commit 19a3b6e12da2 · 2026-01-20T17:10:13.000+01:00
diff --git a/pymodbus/transaction/transaction.py b/pymodbus/transaction/transaction.py
@@ -180,7 +180,7 @@ async def execute(self, no_response_expected: bool, request: ModbusPDU) -> Modbu
                         raise ModbusIOException(
                             f"ERROR: request uses device id={request.dev_id} but received {response.dev_id}."
                         )
-                    if response.transaction_id != request.transaction_id:
+                    if response.transaction_id and response.transaction_id != request.transaction_id:
                         raise ModbusIOException(
                             f"ERROR: request uses transaction id={request.transaction_id} but received {response.transaction_id}."
                        )

Original file line number	Diff line number	Diff line change
`@@ -180,7 +180,7 @@ async def execute(self, no_response_expected: bool, request: ModbusPDU) -> Modbu`
`180`	`180`	`raise ModbusIOException(`
`181`	`181`	`f"ERROR: request uses device id={request.dev_id} but received {response.dev_id}."`
`182`	`182`	`)`
`183`		`- if response.transaction_id != request.transaction_id:`
	`183`	`+ if response.transaction_id and response.transaction_id != request.transaction_id:`
`184`	`184`	`raise ModbusIOException(`
`185`	`185`	`f"ERROR: request uses transaction id={request.transaction_id} but received {response.transaction_id}."`
`186`	`186`	`)`