@mangar2/rs485interface v1.0.2

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
• Global Functions
  • prepare
• Class AddressChain
  • Methods
    • insert
• Class RS485Interface
  • Parameters
  • Methods
    • close
    • getSubscriptions
    • handleMessage
    • on
    • run

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

Global functions

prepare

prepare (config, rs485Interface)

Creates a new rs485Interface object , if not already existing

prepare Parameters

Class AddressChain

new AddressChain()

Contains an ordered chain of addresses

AddressChain Methods

insert

insert (address, version)

Inserts an address , version pair to an ordered address chain

insert Parameters

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

handleMessage

handleMessage (message)

Processes an incoming mqtt message

handleMessage Parameters

on

on (event, callback)

Sets a callback .

on Parameters

on throws

run

async run ()

Starts the server