A method for detecting locking states in communication and/or control appliances (SGi) dispersedly networked together by a data bus (2) compares a message currently transmitted by a communication and/or control appliance (SGi) to a previously transmitted message. It determines and the absence of a locking state of the communication and/or control appliance (SGi) if the messages are different. A message counter is encoded in the transmitted message if the messages are identical and decodes the message counter in a communication and/or control appliance (SGi) receiving the message. It determines the absence of a locking state at the communication and/control appliance (SGi) if the value of the message counter has changed relative to a previous value of the message counter of a previously transmitted message and determines a locking state of the communication and/or control appliance (SGi) if the message counter value has not changed after a specific waiting time (tw).