Default Responses

The ZCL provides a default response which is generated in reply to a unicast command in the following circumstances:

• When there is no other relevant response and the requirement for default responses has not been disabled on the endpoint that sent the command.

• When an error results from a unicast command and there is no other relevant response, even if the requirement for default responses has been disabled on the endpoint that sent the command.

The default response disable setting is made in the bDisableDefaultResponse field of the structure tsZCL_EndPointDefinition detailed in Section 6.1.1. This setting dictates the value of the ‘disable default response’ bit in messages sent by the endpoint. The receiving device then uses this bit to determine whether to return a default response to the source device.

The default response includes the ID of the command that triggered the response and a status field (see Section 6.1.9). Therefore, in the case of an error, the command ID field of the default response contains the the identity of the command that caused the error.

Note: The default response can be generated on reception of all commands, including responses (for example, a ‘read attributes’ response) but not other default responses.

Parent topic:ZCL Fundamentals and Features