Cloud to Device (C2D) messages

Device Command C2D

When receiving the C2D messages using an MQTT client implementation, ensure that MQTT messages are acknowledged at the MQTT level (QOS1). Otherwise, the device may receive repeat C2D messages if it disconnects and comes back online within a short time.

The following JSON will be received by the device when there is any command sent from the IoTConnect portal.

{
    "ct": 0,
    "v": 2.1,
    "cmd": "A String represents the command text",
    "ack": "A string represents guid as the acknowledgement id",
}
** "ack": is optional, required when command has acknowledgement

{
    "ct": 0,
    "v": 2.1,
    "cmd": "A String represents the command text",
    "id": "A string represents child device UniqueID",
    "ack": "A string represents guid as the acknowledgement id",
}
** "ack": is optional, required when command has acknowledgement

OTA Command C2D

The following JSON will be received by the device when there is any OTA sent from the IoTConnect portal.

{
    "ct": 1,
    "v": 2.1,
    "cmd": "ota",
    "ack": "A string represents ota acknowledgement guid",
    "sw": "1.0.0",
    "hw": "1.0.0",
    "urls": [{
            "url": "A string represents downloadable OTA update url with expiry",
            "fileName": "A string represents ota filename with extension"
        }
    ]
}
** "cmd": command text, default is ota, can be changed from template

{
    "ct": 1,
    "v": 2.1,
    "cmd": "ota",
    "ack": "A string represents ota acknowledgement guid",
    "sw": "1.0.0",
    "hw": "1.0.0",
    "urls": [{
            "url": "A string represents downloadable OTA update url with expiry",
            "fileName": "A string represents ota filename with extension",
            "tg": "A string represents tag of device"
        }
    ]
}
** "cmd": command text, default is ota, can be changed from template

Module Command C2D

The following JSON will be received by the device when there is any module push sent from IoTConnect portal.

{
    "ct": 2,
    "v": 2.1,
    "ack": "A string represents ota acknowledgement guid",
    "urls": [{
            "url": "A string represents downloadable OTA update url with expiry",
            "fileName": "A string represents ota filename with extension"
        }
    ]
}
** "ack": is optional, required when module has acknowledgement

Other Commands C2D

The platform can send the below command to ask the device to do some operation. This can be a metadata update request or stop communication etc. All these messages will have the below format, based on the type of device that must react.

{
    "ct": 101
    "v": 2.1
}
** "ct": // Number represents the command type; possible values can be 101 to 111

Possible values of ct can be

105 – Data Frequency Change Message:
{
    "ct": 105,
    "v": 2.1,
    "df": 30
}

110 - Start Heartbeat command:
{
    "ct": 110,
    "v": 2.1,
    "f": 5
}
** "f": A number (in seconds) represents new frequency of sending heartbeat from device