@mangar2/arduinors485 v0.1.1

Abstract

Interface service to communicate with several arduino or similar microcontroller based on a RS485 bus The underlying protocol is token based . Tokens are send from one arduino to the other . The arduino having the token may send . Data is send in an internal message format . The message contains :

• Byte : Sender address
• Byte : Receiver address
• Byte : Reply ( bit 1 ) and message format version ( bit 2 . . 8 )
• Byte : Message length
• Byte : Command to handle
• Word : ( 2 bytes ) value , usual positive integer
• Word : CRC16 for error handling

Contents

• Meta
• Class RS485Interface
  • Parameters
  • Methods
    • close
    • getSubscriptions
    • on
    • processMessage
• Class SerialConnection
  • Methods
    • close
    • listAvailablePorts
    • on
    • open
    • sendData

Meta

• Byte : Sender address
• Byte : Receiver address
• Byte : Reply ( bit 1 ) and message format version ( bit 2 . . 8 )
• Byte : Message length
• Byte : Command to handle
• Word : ( 2 bytes ) value , usual positive integer
• Word : CRC16 for error handling | | Author | Volker Böhm | | Copyright | Copyright ( c ) 2020 Volker Böhm | | License | This software is licensed under the GNU LESSER GENERAL PUBLIC LICENSE Version 3 . It is furnished "as is" , without any support , and with no warranty , express or implied , as to its usefulness for any purpose . |

Callback definitions

Publish

Callback to publish messages to the mqtt broker

Publish Parameters

Send

Callback to send an array of bytes to a receiver

Send Parameters

Data

Called when at least one byte has been read from the serial connection

Class RS485Interface

new RS485Interface(options)

Creates a service class to communicate with several arduino over a RS485 bus Most options are preset ( see "configuration . js" for all presets ) . You must provide the serial port name in operating system format and a list of addresses as object

Example

const serialPortName = 'COM1'
// Do not use 0 or 1 as addresses. 0 is used for broadcast events and 1 is the
// default address of this service.
const addresses = {
   myFloor/myRoom/myDevice: 2,
   myOtherFloor/myOtherRoom/myDevice: 3
   ...
}
const arduinoService = new ArduinoRS485({ serialPortName, addresses })

RS485Interface Parameters

options properties

RS485Interface Methods

close

async close ()

Stops the service

getSubscriptions

getSubscriptions () => {Array.<Object.<topic:string, qos:number>>}

Gets the list of required subscriptions for this service

getSubscriptions returns

on

on (event, callback)

Sets a callback .

on Parameters

on throws

processMessage

processMessage (message)

Processes an incoming mqtt message

processMessage Parameters

Class SerialConnection

new SerialConnection()

Class shielding the serial port class and provides async interfaces The functions open , close , and send data are async functions . Read data by registering the callback 'data' with the on function

SerialConnection Methods

close

async close ()

Closes the serial port

listAvailablePorts

async listAvailablePorts ()

Lists all available ports to console

on

on (event, callback)

Sets a callback .

on Parameters

on throws

open

async open (serialPortName, baudrate) => {Promise}

Opens the serial port

open Parameters

open returns

sendData

async sendData (byteArray) => {}

Sends data to the serial port

sendData Parameters

sendData returns