MQTT

Tentacle PLC publishes it's variables to every configured MQTT broker.

Configuration

Connections to MQTT brokers are configured in config.json (see Configuration). See this example mqtt key of config.json:

{
  "mqtt" : {
    "mosquitto1": {
      "description": "Mosquitto Server 1",
      "rate": 1000,
      "config": {
        "serverUrl": "ssl://192.168.1.3:1883",
        "groupId": "group1",
        "username": "user",
        "password": "password",
        "edgeNode": "edgeNode1",
        "deviceName": "tentaclePlc1",
        "clientId": "tentaclePlc1",
        "version": "spBv1.0"
      }
    }
  }
}

Description

description

Rate

rate

Config

config

Variables

Each variable in variables.json (See Variables) is published using the Sparkplug B specification.

For example, a simple variables.json like this:

{
"count": {
  "datatype": "number",
  "initialValue": 0,
  "description": "A counter.",
  "persistent": true
}

with the mqtt configuration shown above Tentacle PLC will publish data on the topic spBV1.0/group1/DDATA/edgeNode1/tentaclePLC1 to the mosquitto1 broker, and the structure of the payload will look something like this:

{
  "`timestamp": 1486144502122,
  "metrics": [{
    "name": "count",
    "timestamp": 1486144502122,
    "dataType": "Int32",
    "`value": 0
  }],
  "seq": 0
}

TIP

If the datatype of the variableis number, TentaclePLC will determine the dataType for you based on the value of the variable.

Tentacle PLC implements all of the features of MQTT Sparkplug B. If you'd like to learn more about it you can read the specification from the Eclipse Foundation.

Classes

All properties and functions of class instances are published as well, regardless of whether they are set in the variables property of the class.

Functions

Class functions are a little different than other properties. If a function has no arguments, it will be published as a boolean datatype and a remote client can run the function on Tentacle PLC by setting the boolean value to true. If a function has arguments, the function can be run by publishing an appropriately formatted json string with the arguments in it.

Example Using Ignition

Here's an example using Inducutive Automation's Ignition, a modern HMI software that is compatible Sparkplug B:

With the following files:

/runtime/variables.js

{
  "count": {
    "datatype": "number",
    "initialValue": 0,
    "description": "The number of times the main task has been run.",
    "persistent": true
  },
  "countSecondary": {
    "datatype": "number",
    "initialValue": 0,
    "description": "The number of times the secondary task has been run.",
    "persistent": true
  },
  "tone": {
    "datatype": "boolean",
    "initialValue": false,
    "description": "Tone on stack light in JAR office.",
    "persistent": true,
    "source": {
      "type": "modbus",
      "name": "ioThinx4510",
      "rate": 1000,
      "params": {
        "register": 2,
        "registerType": "COIL",
        "format": "BOOLEAN"
      }
    }
  },
  "greenLight": {
    "datatype": "boolean",
    "initialValue": false,
    "description": "Red stack light in JAR office.",
    "persistent": true,
    "source": {
      "type": "modbus",
      "name": "ioThinx4510",
      "rate": 1000,
      "params": {
        "register": 1,
        "registerType": "COIL",
        "format": "BOOLEAN"
      }
    }
  },
  "redLight": {
    "datatype": "boolean",
    "initialValue": false,
    "description": "Red stack light in JAR office.",
    "persistent": true,
    "source": {
      "type": "modbus",
      "name": "ioThinx4510",
      "rate": 1000,
      "params": {
        "register": 0,
        "registerType": "COIL",
        "format": "BOOLEAN"
      }
    }
  },
  "officeTemp": {
    "description": "The temperature in James' office",
    "datatype": "number",
    "initialValue": 0,
    "persistent": true,
    "source": {
      "type": "modbus",
      "name": "groovEpic",
      "rate": 1000,
      "params": {
        "register": 4865,
        "registerType": "INPUT_REGISTER",
        "format": "FLOAT"
      }
    }
  },
  "motor1": {
    "description": "A really great motor",
    "datatype": "Motor",
    "config": {
      "hasRunningInput": false,
      "name": "motor1"
    }
  }
}

/runtime/classes/motor.js

class Motor {
  constructor({ hasRunningInput }) {
    this.functionsFeedback = ''
    this.hasRunningInput = hasRunningInput
    this.prevRunning = false
    this.runtime = 0
    this.startCount = 0
    this.startCommand = true
    this.mode = 'manual'
    this.runtimeInterval = setInterval(() => {
      if (this.running) {
        this.runtime = this.runtime + 1 / 60
      }
      if (this.running && !this.prevRunning) {
        this.startCount = this.startCount + 1
        this.prevRunning = this.running
      }
      if (!this.running && this.prevRunning) {
        this.prevRunning = false
      }
    }, 1000)
  }
  autoRequest() {
    this.mode = 'auto'
    this.functionsFeedback = `${this.name} placed in auto mode.`
  }
  manualRequest() {
    this.mode = 'manual'
    this.functionsFeedback = `${this.name} placed in manual mode.`
  }
  startRequest() {
    if (this.mode === 'manual') {
      this.startCommand = true
      this.functionsFeedback = `${this.name} manually started.`
    } else {
      this.functionsFeedback = `${this.name} cannot be started manually when it is in auto mode.`
    }
  }
  stopRequest() {
    if (this.mode === 'manual') {
      this.startCommand = false
      this.functionsFeedback = `${this.name} manually stopped.`
    } else {
      this.functionsFeedback = `${this.name} cannot be stopped manually when it is in manual mode.`
    }
  }
  get running() {
    if (this.hasRunningInput) {
      return this.runningInput
    } else {
      return this.startCommand
    }
  }
  set running(value) {
    this.startCommand = value
  }
}
Motor.variables = {
  startCount: {
    description: 'Total start count',
    datatype: 'number',
    initialValue: 0,
    persistent: true,
  },
  runtime: {
    description: 'Total runtime',
    datatype: 'number',
    initialValue: 0,
    persistent: true,
  },
  mode: {
    description: 'Current mode (i.e. auto/manual)',
    datatype: 'string',
    initialValue: false,
    persistent: true,
  },
  startCommand: {
    description: 'Start output to the motor.',
    datatype: 'boolean',
    initialValue: false,
    persistent: true,
  },
  prevRunning: {
    description: 'The motor was running during the previous scan.',
    datatype: 'boolean',
    initialValue: false,
    persistent: true,
  },
}

module.exports = [Motor]