modbus-tcp-ip

A simple interface for Modbus over TCP/IP

• Read and write modbus registers
• Support for promises and callbacks

Quick Example

const modbus = require('modbus-tcp-ip')
const device = modbus(ipAddress,port,unitId)
 
//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

const modbus = require('modbus-tcp-ip')
const device = 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