modbus

A simple API for Modbus

  • modbus

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modbus
A simple interface for Modbus
  • Read and write modbus registers
  • One interface for both RTU and TCP
  • Support for promises and callbacks
Quick Example
``` javascript const modbus = require('modbus') //Create a TCP Device const device = modbus(ipAddress,port,unitId) //Create an RTU Device const device = modbus(commPort,baudRate) //Read let myCoil = await device.read('c0') let myHoldingRegister = await device.read('hr0') let myHoldingRegisters = await device.read('hr1-2') //Write await device.write('c0',true) await device.write('hr0',15) ```
Device Object

Constructor

``` javascript const modbus = require('modbus') const tcpDevice = modbus(ipAddress,port,unitId) ```

Properties

  • ipAddress
  • port
  • unitId
  • timeout
  • online

Methods

read(address,callback)

  • address - Coil or register to read.
  • callback(err,res) - Optional.

write(address,value,callback)

  • address - Coil or register to read.
  • value - Data to write.
  • callback(err,res) - Optional.
Address Syntax
Short Hand + Register Number
i.e.
  • 'i8' - Descrite Input 8
  • 'hr418' - Holding Register 418
  • 'hr418-419' - Holding Registers 418 through 419
Applicable Datatypes
``` Data Type Short Hand Size Accessibility Descrite Input i 1 Bit Read Only Coil c 1 Bit Read / Write Input Register ir 16 Bits Read Only Holding Register hr 16 Bits Read / Write ```
Implemented Function Codes
  • FC1 - Read Coil
  • FC2 - Read Input
  • FC3 - Read Holding Registers
  • FC4 - Read Input Registers
  • FC5 - Write Single Coil
  • FC6 - Write Single Register
  • FC15 - Write Multiple Coils
  • FC16 - Write Multiple Registers
Recompile for Electron
If modbus is not compiled for the correct version of Node.js, you will not be able to communicate via Modbus RTU. (Modbus TCP is not affected) When you install modbus it will compile against the version of Node.js on your machine, not against the Node.js runtime bundled with Electron. To recompile modbus (or any native Node.js module) for Electron, you can use electron-rebuild Install modbus: ```sh npm i modbus ``` Install electron-rebuild with --save-dev: ```sh npm install --save-dev electron-rebuild ``` Run electron-rebuild: ```sh $(npm bin)/electron-rebuild ``` Or if you're on Windows: ```sh .\nodemodules\.bin\electron-rebuild.cmd ```