• Documentation
• Device Connection Protocols
• MQTT-based Device Connection
• Common Parameter Description

Common Parameter Description

The following table describes the common parameters used in the request and response messages.

Parameter	Type	Mandatory/Optional	Description
id	String	Optional	The message ID. This is a reserved parameter that is reserved for future use.
version	String	Mandatory	The version of the protocol.
params	JSON	Mandatory in request	The request parameters, in JSON format, which can either be array or dict.
method	String	Mandatory in request	The name of the method.
code	Integer	Mandatory in response	The return code. For a list of common return codes, see Common Return Codes
data	JSON	Optional	The information that is returned. Depending on the return value, it can be in array or dict format.

Common Return Codes

The following list contains common return codes that apply to all EnOS MQTT topics. For return codes that are unique to an MQTT topic, go to the specific topic article in this Device Protocol for MQTT section.

Return Code	Error Message	Explanation
1220	Payload format error	Payload contains invalid JSON format.
1251	Payload is empty	Payload does not contain any content.
1260	Methods not consistent	The method cannot be used for the topic.
1008	Msg size is too large, discard the message	The MQTT message size is too large.
1009	Publish to topic with no write permission	The MQTT topic is not supported, or the device that tried to publish data to the MQTT topic has not logged in to EnOS.