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