MQTT API

The following topics are used for read/write interaction between client and neuron.

The {client-id} in all topics refers to the actual MQTT client id, which is set in the northbound application configuration in the Neuron UI.

Upload Data

Response

Default topic neuron/{client-id}/upload

Body (Tags format)

{
  "node": "modbus-tcp-2",
  "group": "group-1",
  "timestamp": 1647497389075,
  "tags": [
    {
      "value": 123,
      "name": "data1",
    },
    {
      "name": "data2",
      "error": 2014
    }
  ]
}

Body (Values format)

{
    "node": "opcua-1", 
    "group": "group-1", 
    "timestamp": 1650006388943, 
    "values": 
    {
        "cstr01": "hello!"
    }, 
    "errors": 
    {
        "cstr100": 10002
    }
}

TIP

The value is displayed only when the value is read correctly, when the value is read incorrectly, the error code is displayed, not the value.A group sends a message.

The upload topic can be set in the driver configuration form. Once set to a custom topic, the default topic will be disabled.

There are two message formats for the body. You can choose one of two different formats in the mqtt configuration form.

Heartbeat

Response

Default topic neuron/{client-id}/heartbeat

Body

{
  "version": "2.1.0",
  "timestamp": 1658134132237,
  "states": [
    {
      "node": "mqtt-client",
      "link": 2,
      "running": 3
    },
    {
      "node": "fx5u-client",
      "link": 2,
      "running": 3
    }
  ]
}

The heartbeat topic can be set in the driver configuration form. Once set to a custom topic, the default topic will be disabled.

Heartbeat messages are currently set to be sent every 3 seconds by default.

Read Tags

Request

Topic neuron/{client-id}/read/req

Body

{
    "uuid": "E21AEE51-1269-B228-E9E5-CD252CE10877",
    "node": "modbus-tcp-1",
    "group": "group-2"
}

Response

Topic neuron/{client-id}/read/resp

Body

{
  "uuid": "E21AEE51-1269-B228-E9E5-CD252CE10877",
  "tags": [
    {
      "value": 4,
      "name": "data1",
    },
    {
      "name": "data2",
      "error": 2014
    }
  ]
}

TIP

The value is displayed only when the value is read correctly , when the value is read incorrectly, the error code is displayed, not the value.

Write Tag

Request

Topic neuron/{client-id}/write/req

Body

{
    "uuid": "E21AEE51-1269-B228-E9E5-CD252CE10877",
    "node": "modbus-tcp-1",
    "group": "group-2",
    "tag": "tag1",
    "value": 1234
}

Response

Topic neuron/{client-id}/write/resp

Body

{
  "uuid": "E21AEE51-1269-B228-E9E5-CD252CE10877",
  "error": 0
}