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node-red-contrib-modbus v4.1.3

The all in one Modbus TCP and Serial contribution package for Node-RED.

Platform Node-RED Node-RED Modbus NPM version ES_Sourdce_Version ES_Deploy_Version NodeJS_Version Standard - JavaScript Style Guide NPM download Build Status Codacy Badge Percentage of issues still open Average time to resolve an issue


The all in one Modbus TCP and Serial contribution package for Node-RED.


Node-RED contribution package for Modbus

Based on modbus-serial with TCP, C701, Telnet, Serial, RTU buffered, and ASCII

  • stress tested with Node-RED v0.19 and Node.js v9 and v10 LTS
  • works with queueing per unit and round robin scheduling
  • Node.JS 8.x is supported with v3.x
  • Node.JS 6.x is supported with v2.x
  • Node.JS 4.x is supported with v1.x

If you like that contributor's package for Modbus, then please give us your star at GitHub !

You could help as a backer of the project.


Run the following command in the root directory of your Node-RED install

npm install node-red-contrib-modbus

Run the following command for global install

npm install -g node-red-contrib-modbus

try these options on npm install to build, if you have problems to install

--unsafe-perm --build-from-source

modbus-serial, serialport and jsmodbus

The serialport optional dependency is just to list all ports on your system in the client configuration. It is not the serialport version to work with Modbus at runtime. For that check the modbus-serial or jsmodbus package.json, please! The modbus-serial supports and works for TCP connections in that package, too. The jsmodbus package is just to provide a simple Modbus Server node. All Modbus commands running on modbus-serial.

TCP or Serial testing

If you get in trouble with TCP connections, then check and test with just modbus-serial first, please!

If you get in trouble with Serial connections, then check with just serialport first, please!


To update the dependencies or the whole package, you have just to install again.

npm show node-red-contrib-modbus@* version

To get a special version please set the version with @M.M.F:

npm install node-red-contrib-modbus@3.6.1

or global by

npm install -g node-red-contrib-modbus@3.6.1

How to use

Flow Example


Debug will be activated by starting Node-RED with debug mode:

DEBUG=contribModbus*,modbus-serial node-red -v




  • core
    • core:client
    • core:client:fsm
  • io
    • io:core
  • basics
  • read
  • write
  • server
  • response
  • flex
    • flex:getter
    • flex:write
    • flex:connector
    • flex:server
  • modbus-serial

see Wiki pages to get more options in detail


Let's work together! Please read and in best case accept CONTRIBUTING by your sign and send it via E-Mail. You could also send just a pull request or issues while testing, please!

Click here if you want to back the project!


since April 2016 by Klaus Landsdorf


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