@mangar2/rs485interface

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

File	index.js
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 | | 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

Name	Type	Description
message	Message	message to publish

Send

Callback to send an array of bytes to a receiver

Send Parameters

Name	Type	Description
byteArray	Array	Array of bytes

Global functions

prepare

prepare (config, rs485Interface)

Creates a new rs485Interface object , if not already existing

prepare Parameters

Name	Type	Attribute	Default	Description
config	Object			configuration for the rs485 interface
rs485Interface	RS485Interface	optional	null	already existing interface object

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

Name	Type	Description
address	number	address of the element to insert
version	number	version of the element to insert

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

Name	Type	Description
options	Object	configuration options

options properties

Name	Type	Attribute	Default	Description
serialPortName	string			name of the port to use
baudrate	integer	optional	57600	baud rate to be used
myAddress	integer	optional	1	address of this rs485 server
maxVersion	integer	optional	1	maximal suported interface version
tickDelay	integer	optional	100	inner clock managing the token , every action is calculated
timeOfDayDelayInSeconds	integer	optional	60	delay between sending the time of day
qos	0, 1, 2	optional	1	quality of service to send messages
trace	string	optional	'messages'	trace level , supported errors , messages , token

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

Type	Description
Array.<Object.<topic:string, qos:number>>	list of subscription strings

handleMessage

handleMessage (message)

Processes an incoming mqtt message

handleMessage Parameters

Name	Type	Description
message	Message	mqtt message

on

on (event, callback)

Sets a callback .

on Parameters

Name	Type	Description
event	string	event name ( not case sensitive ) for the callback ( supported : 'publish' )
callback	Publish	function ( . . . parameter )

on throws

Type	Description
Error	if the event is not supported
Error	if the callback is not 'function'

run

async run ()

Starts the server